FISH KILL: CAUSES, CONTROL AND IMPACT MITIGATION

Carlito R. Barril, Ph.D Professor of Chemistry (Retired)

UPLB

1

Presentation Outline Introduction Definition Selected fish kill events in the world

Causes of fish kill Types of fish kill Causal factors

Control measures Prevention and investigation Institutional measures Engineering measures

Mitigation of impact Proposed monitoring and warning system

Conclusions

2

Definition(s) Fish kill is defined as localized mass die off of fish that can occur in

marine, estuarine, or freshwaters (Meyer and Barclay, 1990)

Fish kill is a “sudden and unexpected mass mortality of wild or

cultured fish” (Lugg, 2000).

The term fish kill, known also as fish die-off and (in Britain) as fish

mortality, is a localized die-off of fish populations which may also be

associated with more generalised mortality of aquatic life.(Wikipedia)

A single fish kill event can number from several individuals to

millions of dead fish.

3

Definition(s)

Standard definition suggested (La and Cooke, 2011):

An event is considered a fish kill :

a) if the mortality event is not part of the fishes’ natural life cycle (e.g.,

mass mortality following spawning activity in semelparous fish);

(b) if a minimum of 25 dead fish are found in one square kilometre

(lentic) or river kilometre (lotic) and within a 48-hr period, and

(c) if mortality was not caused by predation, including by humans (i.e.,

harvest)

Thus , a single fish kill event can number from 25 to millions of dead fish.

4

Economic Impacts of Fish Kill

Significant economic loss for the fish farm owners

in case of open fishing areas - reducing the population of

recreationally and commercially valuable fish

Reducing source of fish protein available for humans.

cleanup costs

reduced tourism and recreation value

Affects usage of body of water for domestic water supply

Large fish kills also have a negative effect on regulation of food

web dynamics and nutrient balance .

5

Objectives To understand the causes of fish kills and why they occur in order to implement

preventive measures to reduce their frequency and magnitude. Specifically:

Review fish kill events in the world

Understand the different causes of fish kills

Determine the protocols employed in investigating, controlling and minimizing impacts of fish kills.

Propose a protocol for preventing and minimizing impact of fish kills in the Philippines focused on Laguna de Bay

6

Overview of fish kills in the world:

How widespread are the fish kills? Unfortunately, fish kill events are typical and occur worldwide.

Most fish kill events are not isolated, and tend to recur often

(Thronson and Quigg, 2008).

For example, North Carolina reports approximately30 fish kill

events per year since 1996 (NCDWQ, 200 ).

New South Wales reports an average of 34 fish kills per year,

(Koehn, 2004).

Reports of fish kill came also from Kenya (Ochumba, 1990),

Norway (Leivestad and Muniz, 1976), Brazil (Munoz et al.,

1994), United Kingdom,, Ireland, Australia, China, etc.

7

How widespread are the fish kills? In North America, a number of regional summaries of fish kill causes

were reported in Kansas, Missouri, Florida, and North Carolina, and a

national summary for the United States between 1980 and 1989

(Lowe et al., 1991).

Based on EPA data from 1977–1987, estimated 141 million fish die

per year nationally because of fish kills (Pimentel et al., 1993)

A review of all fish kill events that were summarized in both the peer-

reviewed literature and technical reports for North American estuaries

and freshwaters from 1890–2006 (excluding the summaries

produced by Kansas, Missouri, Florida, and North Carolina to avoid

regional bias) identified 170 fish kill events. (see Table 1

8

Table 1a. Some reports on frequency of fish kill events.

Place and date Ave. No. of fish kill

events/year No. of fish killed Reference

USA (1977–1987) >170 141 million per year Pimentel et al.,

1993.

North Carolina,

(1980s) 15 2.5 million Lowe et al., 1991

North Carolina,

USA, 1996 30 Not reported NCDWQ, 2000

North Carolina,

USA, 2008 61 7.5 M NCDWQ, 2008

New South Wales 34 (60-80) Not reported Koehn, 2004

New South Wales

(1980-1989) 16.6 Not reported Lugg, 2000

New South Wales

(1990-1996) 35.7 Not reported Lugg, 2000

Murray-Darling

Basin, Australia

(2002–2004)

3 >5,000 per event Koehn, 2004

9

Trend in number of fish kill reports in the newspapers worldwide

A search for the newspaper articles on fish kills printed in English

was conducted by La and Cooke (2011) covering articles

representative of over 350 major newspapers across North

America, Europe, Australia, Asia, and Africa.

From 1977 thru mid 1980’s - fish kills reported were <

50/year) (see Fig. 1)

Between 1987 - 1994, the number of reports rose steadily to

over 200/year.

By 1997, thru 2007 there were over 800 media reports on fish

kills annually

10

Fig. 1a. - Trend in number of fish kills reported in the newspapers worldwide

11

Table 1b. Selected fish kill events in the world

No. Event/Location Date Count

(Estimate) Species Cause/Remarks

1 Gulf of Mexico (Corpus

Christi)

1935, 22,000,000

Gulf

menhaden, strip

ed mullet,

various other

species[34]

Caused by red tide. This event

caused coughing ,sneezing and

watery eyes in humans. .

1986 22,000,000 Caused by red tide

2 Rhine River, Europe 1986 01 500,000 Caused by spill from Swiss

chemical warehouse.

3 Texas coast, USA 1997–1998 21,000,000 Caused by a bloom of Karenia

brevis

4 White River; West Fork,

Indiana, USA 1999 4,800,000

Caused by discharge of 10000

gallons of chemical HMP 2000 into

the river.

5 River Dee (United

Kingdom) 2002 07

100,000[38

]

salmon, trout, pe

rch

Unconfirmed link to release

of whey into river

6 Neuse River, North

Carolina, USA 2004 09 1,900,000 menhaden

] Natural upwelling of an

acknowledged polluted river.

Hydrogen sulfide smell reported.

7

Liuxihe

River Guangzhou Peopl

e's Republic of China

2008 09 09 10,000 carp Unknown[41][42]

12

Table 1b. Selected fish kill events in the world

No. Event/Location Date Count Species Cause/Remarks

8 Beaches at Thanet,

Kent, England 2010 01 20,000 velvet crab

dead crabs, starfish, lobsters,

sponges and anemones. Probably

killed by hypothermia.

9

Ting

River Fujian People's

Republic of China

2010 07

>1,000,000 Can

feed 70,000

people a year

Part of the Zijin mining disaster

10

Mississippi

River; Plaquemines

Parish, Louisiana, USA

2010 09 >1,000,000

redfish, trout,

pogies, drum,

crabs, shrimp,

BP oil discharge, High T & low tide

11

Jiaxing Xiuzhou

District People's

Republic of China

2011 01

06 250,000

bream, carp,

silver

carp, grass

carp

Only fish caught from a river

under China National Highway

320 east died.

12 Redondo Beach,

California, USA 2011 03 millions

anchovies, m

ackerel, sardi

nes and other

small fish

Caused by oxygen deprivation

13 Nordreisa, Troms,

Norway

2011 12

31 several tons herring [53][54]

14 Guangxi, People's

Republic of China

2012 01

15

40,000

kilograms Various

Caused by 2012 Guangxi cadmium

spill 13

Table 1b. Selected fish kill events in the world No. Event/Location Date Count Species Cause/Remarks

15 Laguna de Bay, Looc 1972, May 20 000 Milkfish Algal bloom of microcystis

16 Laguna de Bay, Central

Bay

1973,

June, July,

August

90% of stocks

killed in

several

fishpens

Milkfish Algal bloom, overstocking,

17 Laguna de Bay, Central

Bay

1975,

June, July

996 ha of

fishpens

affected,

5,000,000

Milkfish Algal bloom, overstocking,

18 Taal Lake, Luzon,

Philippines 2008 01 05

50 metric

tons Tilapia

May be linked to volcanic

activity and large fish farms

19 Taal Lake, Batangas,

Philippines 2011 05 29

750 metric

tons

Tilapia, milkfi

sh

Caused by oxygen depletion and

overstocking

20 Lingayen Gulf, Anda,

Pangasinan, Philippines 2011 05 30

500 metric

tons Milkfish

Oxygen depletion and change of

water climate

21

Laguna de Bay-Jala-jala,

Calamba, Sta. Cruz,

Pakil

2012, May-

June

>10 metric

tons, Not

counted

Tilapia, carp

DO depletion ; Unexplained dead fish

in open waters showed bruises and

cuts

14

Selected fish kill events in the world

Fig. 1b. Massive fish kill at Lake Elmer in Kingfisher Oklahoma, USA

15

Selected fish kill events in the world

Talisay: More than 800 tons of fish have died and rotted on fish farms in a lake near Taal volcano south Talisay: More than 800 tons of fish have died and rotted on fish farms in a lake near Taal volcano south Talisay: More than 800 tons of fish have died and rotted on fish farms in a lake near Taal volcano south Talisay: More than 800 tons of fish have died and rotted on fish farms in a lake near Taal volcano south Talisay: More than 800 tons of fish have died and rotted on fish farms in a lake near Taal volcano south Talisay: More than 800 tons of fish have died and rotted on fish farms in a lake near Taal volcano south Talisay: More than 800 tons of fish have died and rotted on fish farms in a lake near Taal volcano south

Fig. 1c. Massive fish kill in Plaquemines Parish,

West Missippi river, Louisiana USA. Sept. 2010

16

Selected fish kill events in the world

Fig. 1d. Close up of fish kill in Plaquemines Parish, Louisiana due to low tide

and high temperatures. BP oil discharge was also blamed.

17

Selected fish kill events in the world

Fig. 1e. Fish kill in West Pearl river, in New Orleans, LA.

August 17, 2011. Caused by black liquor discharge from a

paper plant. 18

Selected fish kill events in the world

Fig. 1f. Fish Kill in Dubuque, Iowa, linked to Dairy Farm Runoff. USA

19

Selected fish kill events in the world

Fig. 1g. Massive California fish kill. Estimated 1 Million Sardine

Carcasses /March 15th, 2011. Caused by depleted dissolved oxygen

level.

20

Selected fish kill events in the world

Fig. 1h. Large quantities of dead fish floats on Guanqiao Lake in Wuhan, Central

China's Hubei Province . July 11, 2007.

21

Selected fish kill events in the world

Fig. 1i. More than 800 tons of farmed fish in the northern Philippines died

suddenly after the water temperature rose. May, 2011

22

Selected fish kill events in the world

Fig. 1j. Thousands of milk fish float in a cage after a

massive fish kill at Taal Lake, Batangas.

23

Selected fish kill events in the world

Fig. 1k. Talisay: More than 800 tons of fish have died and rotted on

fish farms in Taal lake , Batangas. May-June 2011

24

Causes of Fish Kill

By and large, 66.9% of fish kills are caused by anthropogenic activities,

while only 10.1% were caused by natural events and

23% were undetermined. (NCDWQ,2000; Thronson and Quigg, 2008).

Table 2 shows the distribution of fish kill causes as follows: agricultural pollution (19.5%), biotoxins (17.2%), and chemical pollution (7.1%). Minor causes were extreme changes in temperatures (5.9%), low dissolved oxygen (5.3%), gas bubble trauma (3.6%), disease (3.6%), exhaustion (2.4%), and acidification (1.2%), and undetermined (23%).

25

Table 2a. Common Causes of Fish Kill Cause Frequency

Agricultural pollution - Pertains to pesticide, fertilizer and manure, silo and feedlot

drainage, animal waste, etc.—can be direct or lead to other problems, such as hypoxia

19.5%

Biotoxin - Toxic algal and dinoflagellate blooms that are caused by Karena brevis, Pfiestera, etc. 17.2%

Industrial pollution -Pollution arising from various resource extraction, processing, and

manufacturing activities (e.g., mining, food and kindred products, chemicals, metals, petroleum,

and paper products)

7.1%

Extreme temperature changes - Rapid changes in temperature (e.g., cold shock) 5.9%

Low dissolved oxygen (hypoxia or anoxia)- Low levels of oxygen in the water,

usually associated with urban runoff, algal bloom, decay of organic material (i.e., biological

oxygen demand), rainfall events, etc.

5.3%

Disease - Various bacteria, parasites, fungus, and viruses 3.6%

Gas bubble trauma - Gas-supersaturation downstream from dams or other infrastructure or

natural barriers

3.6%

Exhaustion -Physical exhaustion of fish typically leading to cardiac collapse (e.g., during

challenging migration)

2.4%

Acidification - Acidification by oxidation of sulphide minerals; can be delivered via

precipitation (e.g., acid rain)

1.2%

Municipal pollution - from refuse disposal, water system, swimming pools, power, and sewage

systems

Transportation pollution- Pollution that pertains to rail, trucks, barge or boats, and pipeline

ruptures

Unknown/undetermined - Fish kill events in which no cause can readily be determined 23% 26

Common causes of fish kill

Fish kills -first visible signs of environmental stress;

Common causes :

hypoxia or oxygen depletion,

diseases and parasites,

toxic substances and hazardous wastes,

temperature change,

overstocking,

underwater explosion, etc.

27

Causes of fish kill (Cont’d)

1. What is hypoxia or oxygen depletion ?

Hypoxia, or oxygen depletion, is a phenomenon that

occurs in aquatic environments as dissolved oxygen (DO)

level is reduced to a point where it becomes detrimental to

living aquatic organisms.

DO is typically expressed as % of O2 or mg/L dissolved at

prevailing temp. and salinity (Tables 2a &2b).

States of hypoxia in an aquatic environment is shown in

Table 2c.

28

What is hypoxia or oxygen depletion ?

Temp

DO at 100%

Saturation

DO at 80%

Saturation

DO at 30%

Saturation

oC mg/l mg/l mg/l

0 14.6 11.68 4.38

5 12.8 10.24 3.84

10 11.3 9.04 3.39

15 10.1 8.08 3.03

20 9.1 7.28 2.73

25 8.3 6.64 2.49

30 7.6 6.08 2.28

35 7 5.6 2.1

40 6.5 5.2 1.95

45 6 4.8 1.8

Table 2b. Solubility of oxygen in equilibrium with air in fresh

water (salinity 0) (at P = 1 Atm)

29

What is hypoxia or oxygen depletion ?

Temp

DO at 100%

Saturation

DO at 80%

Saturation

DO at 30%

Saturation

oC mg/l mg/l mg/l

0 11.2 8.96 3.36

5 9.9 7.92 2.97

10 8.8 7.04 2.64

15 7.9 6.32 2.37

20 7.2 5.76 2.16

25 6.6 5.28 1.98

30 6.1 4.88 1.83

35 5.6 4.48 1.68

40 5.3 4.24 1.59

45 4.9 3.92 1.47

Table 2c. Solubility of oxygen in equilibrium with air in sea (salt) water

(at P = 1 Atm)

30

What is hypoxia or oxygen depletion ?

State (Zone) DO Level

(%)

DO at 25oC & 1 Atm in sea water

(mg/L)

Remark

Anoxic or

anaerobic 0% 0 All fish and benthic

organism die

exaerobic >0<1% Boundary between

anoxic & hypoxic

zones

Hypoxic or

dysoxic 1 to 30% 0.07 to 1.98

(2.26 freshwater)

Most fish cannot live

below 30%

―Healthy‖ or oxic ≥80% 5.28

(6.64 freshwater)

5 mg/L is the water

quality criteria for DO

Table 2d . States of hypoxia in aquatic environment

31

Causes of fish kill (Cont’d)

How does algal bloom cause fish kill?

Algal bloom is a term used to describe the profuse growth of

aquatic algae.

It can occur in both fresh water and marine environments.

Algal blooms are often green, but can also be yellow-brown or

red, depending on the species of algae.

One common algal bloom is caused by the blue green algae,

microcystis sp., a cyanobacteria which may resemble a green

blanket covering a body of water during summer especially

when the water is calm. (see Figures )

32

Causes of fish kill (Cont’d)

How does algal bloom cause fish kill?

Fig. 2a. Algal bloom -The thick green waters of Lake Chaohu, China

33

Causes of fish kill (Cont’d)

How does algal bloom cause fish kill?

Fig. 2b. Algal Blooms - Midwest Lakes, USA

34

How does algal bloom cause fish kill?

DO level cycle during an algal bloom:

During the day, DO is high because of the photosynthesizing algae.

At nightime, DO is reduced by the aerobic respiration of all living organisms in the water (see Fig. 2a)

A diurnal cycle of DO level is thus observed, very high during the day and low towards the break of dawn.

Some fish might be distressed at this period but no deaths are yet observed.

35

Diurnal cycle of DO during photosynthesis and

Aerobic respiration

Fig. 2c Aerobic respiration (red arrows) during which both plants and animals

utilize oxygen to metabolize organic compounds that were created through

photosynthesis (green arrow).

36

How does algal bloom cause fish kill?

DO level cycle during an algal bloom:

When the algae bloom collapsed, i.e. the algae died, and sunk to the bottom where they are decomposed by facultative anaerobic organisms

First by facultative bacteria and later, when all DO is depleted, by anaerobic bacteria producing obnoxious products such as NH3 and H2S sulfide which are both highly toxic to fish (see Box #1).

Under these conditions, no fish or any other benthic organisms can live.

And if these bottom waters with zero DO and containing toxic NH3 and H2S are brought up by turnover or any mixing process, then fish kill will surely occur.(see Fig. 2a)

37

How does algal bloom cause fish kill?

Box # 1. Anaerobic decomposition products:

ORGANIC MATTER (C, H, O, N, P, S) Anaerobes CH4, NH3, H2S, CO2,VFA

38

How does algal bloom cause fish kill?

Figure 2d. A simplified model of a summer fish kill mechanism. Critical

levels indicate high fish kill risk. (After Barica 1973, 1975 b)

39

How does algal bloom cause fish kill?

Fig. 2e. Key Indicators before and after algal collapse:

• Secchi disc transparency is only 0.2–0.4 m at bloom phase

• DO high during bloom phase and falls abruptly during the algal collapse and decay

• chlorophyll “a” values of 100–200 ug/1 (algal bloom phase)

• Ammonia at near-zero level starts to increase and reaches maximum after DO drops to zero.

• pH follows DO, high during bloom phase and low during algal decay.

40

Ammonia toxicity to fish Among the effects are:

loss of equilibrium,

Hyper-excitability,

increased breathing,

decrease in nitrogen excretion, not to mention death.

At lower concentrations: reduced hatch and reduced growth rates.

Percentage of toxic un-ionized NH3 vs. NH4+ ion increases with Temp but decreases with pH.

At pH 8.5, - %NH3 is 15.3 at 25oC. and 20.3 at 3ooC

At 3ooC , - %NH3 is 7 at pH 8.0 and 2.48 at pH 7.46

However, toxicity of NH3 increases with decreasing pH. (see Table 2e)

41

Table 2e. Lethal ammonia concentrations for salmon at 86 degrees 30oC (by

pH, and duration of exposure) (EPA, 1985).

pH Duration Lethal* Ammonia Concentration

(mg/l)

Total NH3 Un-ionized NH 3

6.5 1-hr

4-hr

14.3

0.73

0.036

0.002

7.0 1-hr

4-hr

11.6

0.74

0.093

0.006

7.5 1-hr

4-hr

7.3

0.74

0.181

0.019

8.0 1-hr

4-hr

3.5

0.47

0.27

0.035

8.5 1-hr

4-hr

1.3

0.17

0.26

0.035

*LC50 levels at which half of the exposed individuals die. U.S. EPA recommends that these levels should not be exceeded more than once in three years.

42

Common Name Scientific Name Avg Species LC50

(ug/L) LC50 Std Dev Avg Species Rating

Goldfish Carassius auratus 58.4 31.1 Very Highly Toxic

White sucker Catostomus

commersoni 23.4 6.32 Very Highly Toxic

Lake whitefish Coregonus

clupeaformis 15.3 25.9 Very Highly Toxic

Northern pike Esox lucius 38.7 26.9 Very Highly Toxic

Asian redtail catfish Hemibagrus

nemurus 3.20 - Very Highly Toxic

Bluegill Lepomis

macrochirus 23.1 12.3 Very Highly Toxic

Largemouth bass Micropterus

salmoides 78.1 82.5 Very Highly Toxic

Rainbow

trout,donaldson

trout

Oncorhynchus

mykiss 38.0 38.3 Very Highly Toxic

Yellow perch Perca flavescens 35.6 43.4 Very Highly Toxic

Fathead minnow Pimephales

promelas 57.3 93.2 Very Highly Toxic

Brown trout Salmo trutta 7.00 - Very Highly Toxic

Walleye Stizostedion

vitreum 42.0 21.7 Very Highly Toxic

Table 2f. Toxicity of hydrogen sulfide to fishes.(EPA database).

43

How does turnover cause fish kill?

How does heavy rain cause fish kill?

Lake is stratified with high DO in upper layer

(epilimnion) and low DO at the lower layer

(hypolimnion)

During turnover the heavy cold

rainwater sinks causing a mixing of the

two layers

44

How does algal bloom cause fish kill?

Red tide or harmful algal bloom (HAB)

•Algal bloom that causes negative impacts to other

organisms via production of natural toxins, mechanical

damage to other organisms, or by other means.

•HABs are often associated with large-scale marine

mortality events and have been associated with various

types of shellfish poisoning. (see Table )

•Of the 5000+ species of marine phytoplankton that exist

worldwide, about 2% are known to be harmful or toxic.[6]

45

Causes of fish kill (Cont’d)

How does algal bloom cause fish kill?

Fig. 2f. Red tide or Harmful Algal Bloom

46

Causes of fish kill (Cont’d)

How does algal bloom cause fish kill?

Fig. 2g. Red tide or Harmful Algal Bloom

47

How does algal bloom cause fish kill?

Examples of common harmful effects of HABs:

•production of neurotoxins which cause mass mortalities in fish,

seabirds, sea turtles, and marine mammals

•human illness or death via consumption of seafood contaminated

by toxic algae

•mechanical damage to other organisms, such as disruption of

epithelial gill tissues in fish, resulting in asphyxiation

•oxygen depletion of the water column (hypoxia or anoxia) from

cellular respiration and bacterial degradation

48

How does algal bloom cause fish kill?

Toxin HAB species Affected Organisms Remark /effects

Brevetoxins

dinoflagellate Karenia brevis bottlenose dolphins,

manatees, whale

neurotoxin responsible

for neurotoxic shellfish

poisoning

Saxitoxin

dinoflagellate Alexandrium

fundyense

cyanobacteria Anabaena sp

Finfish, shellfish neurotoxin responsible

for paralytic shellfish

poisoning

Domoic Acid

Diatom Pseudo-nitzschia, Mammals, human neurotoxin responsible

for amnesic shellfish

poisoning

Cyanotoxins cyanobacteria (also known

as blue-green algae)

Microsystis, Anabaena,

Planktothrix (Oscillatoria),

Nostoc, etc.

Fish, birds, livestock,

domestic animals

and sometimes

humans.

neutrotoxins,

hepatotoxins,

cytotoxins,

microcystins, and

endotoxins.

Table 2e . Toxins associated with red tides (HABs)

49

Causes of fish kill (Cont’d) 2. Diseases and parasites

Major types of fish diseases

1. Infectious diseases- caused by viruses, bacteria and

fungi

2. Invasive diseases – caused by parasites such as

protozoans, flukes and worms, or crustaceans.

Fish that are stressed for other reasons, such as spawning or

suboptimal water quality, are more susceptible.

In fish farming, where populations are optimized for the

available resources, parasites or disease can spread quickly

50

Causes of fish kill (Cont’d) Diseases and parasites

Pathogens which can cause fish diseases comprise:

viral infections

bacterial infections, such as Pseudomonas fluorescens leading

to fin rot and fish dropsy

fungal infections

water mould infections, such as Saprolegnia sp.

metazoan parasites, such as copepods

unicellular parasites, such as Ichthyophthirius multifiliis

51

Causes of fish kill (Cont’d) Effects of diseases and parasites

Some early warning signs :[10]

Discoloration, open sores, reddening of the skin, bleeding, black

or white spots on the skin, missing scales or lack of slime

Abnormal shape, swollen areas, abnormal lumps, or popeyes

Abnormal activity such as flashing, twisting, whirling,

convulsions, loss of buoyancy

Listlessness, weakness, sluggishness, lack of activity

Loss of appetite or refusal to feed

52

Causes of fish kill (Cont’d)

3.Toxic substances and hazardous wastes

Sources include:

agricultural runoffs carrying pesticides, fertilizers, etc.

industrial wastes containing toxic chemicals and hazardous

wastes such as toxic heavy metals, acidic process waters,

etc.,

hazardous spills such as petroleum products,

Sewage surface runoff containing high organic load

53

Causes of fish kill (Cont’d)

Toxic substances and hazardous wastes

Human-induced fish kills are unusual, but occasionally a spilled

substance causes direct toxicity or a shift in water temperature

or pH that can lead to fish kill.

Some notable fish kills in Louisiana in the 1950s were due to a

specific pesticide called endrin.[

in 1997 a phosphate plant in Mulberry, Florida, accidentally

dumped 60 M gallons of acidic process water into a creek,

reducing the pH to less than 4, resulting in the death of about

1.3 million fish.[7]

About a million of fish died after an accidental spill of bourbon

whiskey into the Kentucky River. However, officials could not

determine whether the fish kill was due to the bourbon directly or

to oxygen depletion that resulted when aquatic microbes rapidly

began to consume and digest the liquor.[7]

54

Causes of fish kill (Cont’d)

Toxic substances and hazardous wastes

In 1999, about 5 million fish died in White River, Indiana caused

by an automotive parts maker which had discharged 10,000

gallons of the chemical HMP 2000 into the river.

In Jan. 2012, about 40,000 kg of fish died in Guangxi, People's

Republic of China caused by cadmium spill in a river.

Cyanide is a particular toxic compound that has been used to

poach fish. In cyanide poisoning the gills turn a distinctive cherry

red.

Chlorine introduced as alkaline hypochlorite solution is also

extremely toxic leaving pale mucilaginous gills and an over-

production of mucilage across the whole body.

55

Causes of fish kill (Cont’d)

4. Climate change: drought & temperature change

Fish kills can also result from a dramatic or prolonged drop

in air (and water) temperature.

This kind of fish kill is selective – usually the dead fish are

species that cannot tolerate cold.

Tilapia are unable to survive in temperate climates because

they require warm water. Most species of tilapia will die at a

range of 52 to 62 °F (11 to 17 °C).

56

Causes of fish kill (Cont’d)

Climate change: drought & temperature change

A fish kill can occur with rapid fluctuations in temperature or sustained high temperatures.

A period of sustained high temperatures can lead to decreased DO in a body of water.

An August, 2010, fish kill in Delaware Bay was attributed to low oxygen as a result of high temperatures.[23]

In September, 2010, a massive (millions) fish kill at the mouth of the Mississippi River in Louisiana, was attributed to a combination of high temperatures and low tide. BP oil discharge was also blamed.

57

Selected fish kill episodes in the world

Fig. 2d. Massive fish kill in Plaquemines Parish, West Missippi river, Louisiana, Sept. 2010 due to low tide and high temperatures.

58

Causes of fish kill (Cont’d)

5. Droughts and overstocking

A drought can lead to lower water volumes to the extent that the reduced volume may not be enough for the fish population.

Droughts often occur in conjunction with high temperatures so that DO level is also reduced.

Low river flows also reduce the available dilution for permitted discharges of treated sewage or industrial waste.

The reduced dilution increases the organic demand for oxygen further reducing the oxygen concentration available to fish.

Overstocking of fishpen can also result in fish kills!!!

59

Causes of fish kill (Cont’d)

6. Underwater explosions and emissions

Underwater explosions can lead to fish kill, and fish with swim

bladders are more susceptible.

Sometimes underwater explosions are used on purpose to

induce fish kills, a generally illegal practice known as blast

fishing.

Underwater explosions may be accidental or planned, such as

for construction, seismic testing, mining or blast testing of

structures under water.

Volcanic emissions resulting in the release of H2S which is very

toxic to fish.

60

CONTROL AND PREVENTION OF FISH KILL

Knowing and understanding the different causes

of fish kill, how can we control or prevent them?

First we start with those factors caused

anthropogenically which comprised about 80% of

all causes.

Foremost among this is anoxia caused by

several factors such algal bloom, dumping of

high BOD wastes like sewage, garbage, oil, etc.

61

CONTROL AND PREVENTION OF FISH KILL

1. Control of hypoxia or oxygen depletion

When algal bloom is apparent, reduce algal bloom density by

chemical treatment using herbicide/algaecide, to maintain SD

transparency above 60 cm.

Do not kill all the algae but treat 1/3 of your pond/farm at a time

and avoid treatment on extremely hot sunny days. Treat early

before the onset of calm summer days before April.

Do not overstock fish.

Avoid over feeding. Use feeding trays to minimize unused feeds

from falling down to the bottom.

62

CONTROL AND PREVENTION OF FISH KILL

Control of hypoxia or oxygen depletion (cont’d)

Prevent or minimize surface run-off of wastes with high BOD load into your immediate surroundings.

Check BOD load of sediment under the fishpen area and make sure it does not exceed the WQ criteria.

Monitor key WQ parameters such as DO, SD, pH, T, NH3 , Chla.

Check DO level daily at the break of dawn during summer or when nearing harvest time.

Install an emergency aeration system – either subsurface or surface aerators to maintain DO level above 4 mg/L.

63

CONTROL AND PREVENTION OF FISH KILL

2. Control of fish disease and parasites

General knowledge of fish disease control:

Focus on prevention rather than treatment.

Knowledge of what pathogens and parasites affect the stock. (see Fig. 4a)

Sanitation practices to prevent infection or introduction of pathogens and parasites.

Regularly check presence of disease and parasites

Diagnosis and treatment of fish diseases

Get services of a fish disease specialist or veterinarian

64

Control and prevention of fish kill

Fig. 4a. Control of diseases of Tilapia – pathogens at different stages of culture

65

3. Protocol for Prevention and investigation

A major problem with current fish kill investigations is that there is no globally accepted standard protocol.

Many countries in the developed world have specific provisions in place to encourage the public to report fish kills[30] so that a proper investigation can take place.

Investigation of the cause of a kill requires a multi-disciplinary approach including: a) on-site environmental measurements,

b) investigation of inputs,

c) review of meteorology and past history,

d) toxicology,

e) fish autopsy,

f) invertebrate analysis and

g) a robust knowledge of the area and its problems.

66

Protocol for Prevention and investigation One good protocol to follow is the national investigation and reporting

protocol by the Commonwealth of Australia (2007).

It sets a standard minimum requirements for each stage of management of a fish kill incident and includes:

a) useful flowcharts,

b) information on sampling methods,

c) the roles and responsibilities of officers assigned to fish kills investigation, and

d) resources for investigating officers.

Some states in the USA have their own protocols for fish investigations, but these are localized in approach and difficult to adopt by less developed countries.

In view of this, La and Cooke (2011) proposed a framework for a more scientific and systematic approach to fish kill investigation, determining the proximate and ultimate causes and promulgating action plan for its prevention and impact mitigation that can be adopted worldwide (Table 3a).

67

Table 3a. Framework for fish kill investigation (adopted from Meyer

and Barclay, 1990) Generalized

Investigation Steps

Current Status and Challenges Opportunities for Improvement

1. Fish kill reported/

suspected

by fax, mail, or telephone by

public

Can be tedious and time-

consuming

Time lag between fish kill

notification and scientific

investigation

Reporting by web-based submission or

phone call using fish kill hotlines

Reduce time lag between fish kill

notification and scientific investigation

2. Investigator

designated

Often regional biologist with

little expertise on fish kill

investigation

Create training programs for two sets of

investigators (1) First responder:

general knowledge of fish kills and

ability to take samples (2) Specialist:

specialized in fish kill research and has

knowledge of all assessment methods

and investigative tools

3. Site visit for

reconnaissance

Few visits per kill; often delayed or

non-existent

Implement long-term monitoring

programs

No standard protocol

Require more site-visits per kill

immediately after fish kill is

reported/suspected

Create standard protocol

68

Generalized

Investigation Steps

Current Status and Challenges Opportunities for Improvement

4 Collect chemical, physical, and biological samples

Often delayed resulting in

degraded samples

Few samples taken

No control to compare pre-

fish kill to post-fish kill

Conditions

Implement long-term monitoring

programs

Take more samples, taking into

account biological Variation

Consider using reference sites

Adopt interdisciplinary approach

5 Fish kill count to

evaluate resource

damage and

monetary value

assessment

Often underestimated

Scavengers remove

carcasses

Economist value

assessments on species for

compensation costs

Take into account scavengers and

difficulties in detecting dead fish

Continue value assessments of

species and number of fish killed for

compensation

Conduct studies to understand

counting biases

6 Laboratory analysis

and database

mining

Samples often degraded or

limited; difficult for

pathological analysis

Collection of more samples

immediately after fish kill reported

Adopt interdisciplinary approach in

data analysis

Table 3a. Framework for fish kill investigation (Cont’d.)

69

Table 3a. Framework for fish kill investigation (Cont’d.)

Generalized

Investigation Steps

Current Status and Challenges Opportunities for Improvement

7. Collate and

synthesize

information

Information prior to fish kill

unavailable, difficult to determine

causation

Most investigations try to identify a

single cause, but in reality rarely reveal

more than correlation

Consider several factors as most

fish kill causes are complex

Consider carry-over effects

8 Prepare a report Non-existent in some jurisdictions,

while others compile annual regional

reports

Implement annual reporting on

regional/national/global levels on

fish kills

Publish case studies in peer-

reviewed outlets

9 Regulatory or

management

action response

to those causes

• Some monitoring; most do not have

fish kill management plans

• Reactive approach to fish kills rather

than attempting to predict and prevent

events

• Implement long-term monitoring

programs

• Identify potential causes and

structure management action in

response to those causes

• Adopt a proactive approach to

fish kill prevention

70

National Protocol for prevention and investigation of fish kill

In line with the framework proposed above, the Philippines

should strive to formulate a national protocol for investigation

and prevention of fish kills.

The national agencies and instrumentalities involved in the

management of our aquatic and marine resources such as the

PCAMRD, BFAR, DENR, LLDA, etc. should collaborate for the

formulation of the national protocol.

In the mean time, I would venture to propose a fish kill

management framework plan for Laguna de Bay

71

Framework Plan for the Control and Impact Mitigation of

Fish Kill in Laguna de Bay

This plan consists of two phases:

Phase 1. Review and Cause Analysis of Fish Kills in Laguna de Bay and Other Places

Based on this review, the causal factors will be identified,

classified, and their specific effects will be ascertained

based on observation and scientific findings.

For quantifiable factors the critical level of toxicity to fish and

other impacts will be determined from published data.

Table 1 shows the different factors to be considered.

72

Framework Plan for the Control and Impact Mitigation of Fish Kill in Laguna de Bay

Phase 1: Table 1 - Data and information to be collected

1. Spatial data and stocking density

Location of fish kill

Density of fish pens in the lake (% of surface area, by location i.e. East, West, or

South Bay)

Stocking rate (number of fingerlings per square meter)

Feeding practice (method, frequency and quantity per stocking load)

Water depth in the affected area

Proximity to anthropogenic sources of toxic pollutants (nearby factories, industrial

establishments, agricultural runoffs, sewage & garbage disposal, etc.)

2. Temporal data

What season of year fish kill occurred

Which months fish kill more prevalent

Duration of fish kill

3. Fish health data

Occurrence of fish diseases

Presence of parasites

Other threats to fish health such as toxins, knifefish attacks, etc.

73

Framework Plan for the Control and Impact Mitigation of Fish Kill in Laguna de Bay

Phase 1: Table 1 (Cont’d) 4. Water Quality Data –Trend in the bio-physicochemical parameters in the last

20 years

Dissolved oxygen (DO)

Biochemical /chemical oxygen demand (BOD/COD)

Temperature

pH

Secchi disc readings

Chlorophyll a

Seasonal variation

5. Hydrological/Meteorological data

Water currents in the lake, seasonal changes,

Rainfall (monthly and annual data)

Wind direction (moonsons – months & duration)

Etc.

6. Carrying Capacity Study of Laguna de Bay

74

Framework Plan for the Control and Impact Mitigation of Fish Kill in Laguna de Bay

Phase 2: Development of a monitoring and warning system for preventing fish kill

Based on the results of Phase 1, a model monitoring and warning system that could prevent or

signal an impending fish kill will be developed, tested and deployed in strategic places.

Pending the results of Phase 1 study, the conceptual framework for this monitoring system is

envisioned to have four components:

a) a set of policy and regulatory measures and guideline on fishpen zoning, stocking density,

feeding rate and frequency;

b) monitoring of key water quality parameters such as pH, Temperature, DO, BOD/COD, Total

Ammonia, Secchi disc reading, and Chlorophyll a or algal growth,

c) Fish health management measures, and

d) stakeholders and communication network.

A set of critical values for key water quality parameters will be formulated to serve as warning or

alert levels to institute remedial measures before a critical condition for fish kill is reached.

Table 2 shows the conceptual framework for the monitoring and warning system.

75

Phase 2: Table 2 Conceptual Framework for the Monitoring and Warning

System for Fishkill Prevention

Factors Guideline

1. Policy and regulatory measures to be imposed and monitored

Fish pen zoning - based on

physiographic and hydrological data

Total fishpen area – based on carrying

capacity data

Stocking density – must not exceed the

optimum or maximum prescribed by

BFAR

Feeding practice –method, frequency,

quality and quantity of feeds,

Where to locate, density of fishpens

What is total fishpen area to be allowed

in the Lake?

Maximum number per cubic meter

Feeding method, frequency rate, quality

and quantity of feed per fingerling,

2 Fish health management measures

Fish disease prevention and detection

Parasites control

Fish farm sanitation practice

Aerators

How to detect and prevent fish diseases

How to control parasites

Proper sanitation practices

Need for aerators

76

Phase 2: Table 2 (Cont’d) Factors Guideline

3. Monitoring of key water quality parameters to detect critical levels*

pH

Temperature

Dissolved Oxygen

BOD/COD

Total Ammonia

Secchi disc transparency (Turbidity)

Chlorophyll a or algal growth

6.5 -8.5

Ambient ± 3oC

>5.0 mg/L

< 10/20 mg/L

0.17- 0.73 mg/L (pH & T dependent)

20 -40 cm (Class C criteria=100 cm)

< 100 μg/l (as chlorophyll “a”) ,

How to prevent algal bloom

4. Stakeholders and communication network

Involvement of stakeholders - (LLDA, LGUs,

Fishpen owners, fishermen, etc.)

Mass education of the people on the scientific

aspect and risk involved

Communication network to enhance

exchange of information among stakeholders

involved

Led by LLDA or a management group

Proper education of the people especially

fishermen and fishpen operators

Set up an early warning system based on

modern communication facilities.

77

CONCLUSIONS Review of fish kills events revealed a widespread and worldwide occurrence

of this phenomenon in both freshwater and marine environments.

A survey of fish kill reports in 350 major newspapers representing the major continents except South America shows an exponential increase from less than 50 fish kill events per year in the 1970s to about 900 events per year in the 1990s before leveling off beyond year 200.

Determination of the causes of fish kills shows that majority (about 70%) are due to anthropogenic activities with only 10.1 % due to natural events, while 23% were unknown or undetermined.

Agricultural pollution topped the list of anthropogenic causes with 19.5% followed by biotoxins from harmful algal blooms with 17.2% and the rest with contributions below 10 %.

Extreme temperature changes, either too hot or too cold, is the top natural cause of fishkill.

78

CONCLUSIONS (Cont’d) The common ultimate cause of fish kill reported is low DO (hypoxia or

anoxia) which is associated with urban runoff, algal bloom, decay of organic material, rainfall events, drought and prolonged high temperature, etc.

The common control or preventive measures for fish kill are algal bloom prevention, prevention of runoffs with high BOD load, no overstocking, no overfeeding, detection and treatment of fish diseases and parasites, and installation of emergency aeration systems.

The need for the formulation of a national protocol for investigation and prevention of fish kills is suggested.

A framework plan for the development of a monitoring and warning system for the prevention of fish kills in Laguna de Bay is proposed.

79

SALAMAT PO

THANK YOU

ARIGATU GOSAIMAS DESU

SALAMAT PO

THANK YOU

Arigatōgozaimashita

80

Have a blessed day!

81

St. Peter’s Fish

82