marine fisheries and conservation of marine resources
DESCRIPTION
Marine Fisheries and conservation of marine resources. What are fisheries? How do we use marine resources? How do manage marine resources?. What is a Fishery?. A Fishery is made of 3 parts: the population fished. The economics behind the fishery. The fishermen. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/1.jpg)
Marine Fisheries and conservation of marine resources.
1. What are fisheries?
2. How do we use marine resources?
3. How do manage marine resources?
![Page 2: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/2.jpg)
What is a Fishery?A Fishery is made of 3 parts:
1. the population fished.
2. The economics behind the fishery.
3. The fishermen.
![Page 3: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/3.jpg)
Examples of several fisheries
![Page 4: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/4.jpg)
Different types of Fishermen
• Large-scale commercial fishermen
• Small scale commercial fishermen
• Subsistence fishermen
• Recreational fishermen
![Page 5: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/5.jpg)
Commercial Divers: Hookah divers in Mexico
Hookah divers in Mexico use an air compressor and long hoses to fish for benthic species.
Underwater these divers collect octopus, scallops, clams, oysters, benthic fish, snails, and sea cucumbers.
![Page 6: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/6.jpg)
Hookah divers near Penasco hunt for Murex snails which are taken to a plant and processed.
![Page 7: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/7.jpg)
Any questions so far?
![Page 8: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/8.jpg)
Moving on:
1. Types of fishing and fishing gear.
2. Economics of fisheries and fisheries decline.
![Page 9: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/9.jpg)
Stock - a key concept
• A stock is a geographically definable population of a species that changes abundance in response to factors, relatively independently of other stocks
![Page 10: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/10.jpg)
Stock - a key concept 2
• Managers wish to identify stocks to manage and regulate crucial factors, such as controls on food eaten by the stock, crucial nursery grounds, sharing of stocks between political entities, such as different states or countries
![Page 11: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/11.jpg)
Identification of Stocks
• Tags - devices inserted into fish so that they can be located subsequently and the location can be related to the site of tagging
• Biochemical and molecular markers - used to distinguish between stocks. If individual populations have unique markers, they are separated evolutionarily from other stocks
![Page 12: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/12.jpg)
Gulf Coast bands
Atlantic bands
Mitochondrial DNA markers used to identify stocksof Striped Bass, Morone saxatilis
![Page 13: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/13.jpg)
Crucial Life History Information Needed
• Range of temperatures and salinities for maximum growth
• Location of spawning/nursery habitat• Location of feeding areas• Biological information that minimizes
unintended mortality during fishing
![Page 14: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/14.jpg)
Stock Size
• Landings from fisheries are the main means of estimating stocks, although scientific sampling is also done
![Page 15: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/15.jpg)
Stock Size 2
• Landings can be related to stock size (= local population size) if relation to fishing effort can be determined
![Page 16: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/16.jpg)
Stock Size 3
• Fishing effort is a function of (1) number of boats; (2) number of individuals fishing; (3) hours spend fishing; (4) efficiency of fishing gear
![Page 17: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/17.jpg)
Stock Size 4
• Stock estimates take into account the catch per unit effort
![Page 18: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/18.jpg)
Landings of the blue whale, as compared with effort
1931 32 40 47 50 60 1963
Year
Cat
ch p
er c
atch
er-d
ay’s
wor
k
![Page 19: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/19.jpg)
Fisheries Model
• To understand the behavior of a fishery, we have to construct a model of population change
• We must have an idea of the life history, which includes the mode of reproduction, the number of young produced, the survivorship, growth periodicity (seasonal) and rate of growth)
![Page 20: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/20.jpg)
Nursery area Reproduction
Recruitment
Mortality
To produce a good fisheries model, we must account for allcontributions to reproduction, growth, and mortality, throughout the life cycle of the fishery resource species.
![Page 21: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/21.jpg)
Stock Recruitment Models
• Objective of model is to predict recruitment (the number of newly born that enter and are noticed in the first year class - 0+ )
![Page 22: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/22.jpg)
Stock Recruitment Models 2
• Model presumes that recruitment can be predicted on basis of stock in previous year
![Page 23: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/23.jpg)
Stock Recruitment Models 3
• Model presumes that recruitment increases with increasing stock size, up to a maximum, then recruitment decreases because a stock of increasing size will be more and more limited by food and will produce proportionally fewer new recruits
![Page 24: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/24.jpg)
0 400 800 1200 1600
120
40
80
0
Stock in previous year
Rec
ruitm
ent
Stock-recruitment model
Density-dependenteffects
![Page 25: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/25.jpg)
Maximum Sustainable Yield
• Based on idea that a fishery stock will grow at a slower rate over a certain stock size
• Idea is to fish the stock down to the population level where growth is maximal
• Leads to management tool to determine fishing pressure
• Not much evidence that this approach works, even if the theory makes some sense
• Problem might be that factors other than simple density dependence affect stock size
![Page 26: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/26.jpg)
Fishing Techniques
• Hooking fishes individually - e.g., long lines with rows of hooks
• Entangling fishes in nets - e.g., large drift nets, nets towed below the surface and kept open with wooden boards
• Traps - e.g., baited lobster traps kept on bottom
• Diving for fisheries (collection by hand)
![Page 27: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/27.jpg)
Hooking Fishes Individually
AnglingHand line
Demersal long lineFloating long line
![Page 28: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/28.jpg)
Drift nets
Set nets
Pelagic trawlPurse seine
Bottom otter trawl
Fishing with nets
![Page 29: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/29.jpg)
Stock Reduction - factors
• Environmental change• “Random factors”• Overfishing
![Page 30: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/30.jpg)
Vulnerable Fisheries
• Life histories with long generation times• Life histories with low fecundity• Stocks with confined populations
(aggregations or geographic range in a confined area)
• Resource species that are easily caught
![Page 31: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/31.jpg)
Management Problems 4• Fisheries managed by a variety of local and federal
agencies• Management recommendations not always in best
interests of maintaining stock• Some policies backfire - e.g., Magnuson Act of 1976
which extended US coastal fishing zone 200 miles from shore but resulted in extensive deployment of US fishng boats, resulting in overexploitation
• Magnuson Act established 8 regiona fishing commissions to help regulate domestic fishing - results good in some cases, bad in others
![Page 32: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/32.jpg)
Effects of Overfishing 4• Great reduction of many stocks, e.g., formerly productive
Georges Bank, east of New England• Effects concentrated especially on species with
vulnerable life cycles (low fecundity, long generation time - e.g., sharks, whales)
• Collateral effects on the bottom, where bottom trawling continually turns over the bottom, killing epibenthic animals
• Elimination of species at the tops of food chains, which tend to be lower in abundance and have vulnerable life history characteristics
![Page 33: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/33.jpg)
GEORGESBANK
Atlantic Ocean
Cape CodYear
Met
ric T
ons x
10
3 Georges BankStock landings
Cod
HaddockYellowtail
Trends in landings of three major fisheries on Georges Bankon the New England continental shelf
![Page 34: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/34.jpg)
Some new management tools
• Individual transferable quota (ITQ) - licenses are limited in number with quotas for each license, which can be sold
• Marine Protected Areas (also known as No-Take Areas) - some portion of the stock’s geographic range is closed to fishing - protects spawning grounds, nursery grounds, or minimal crucial habitat size to preserve stock even when fishing is too high
![Page 35: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/35.jpg)
Spawningarea
JuvenileFeeding area
Adult feeding area
Adult feeding area
Adult feeding area
No-take areas
Current and dispersaldirection
Hypothetical No-take Plan
![Page 36: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/36.jpg)
Mariculture - Important Factors
• Desirability as food• Uncomplicated reproduction• Hardiness• Disease resistance• High growth rate per unit area (growth efficiency)• Readily met food and habitat requirements• Monoculture or polyculture• Marketability• Minimal ecological damage
![Page 37: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/37.jpg)
Mussels and Oysters
• Mussels usually recruit to ropes and poles• Placement in areas of high phytoplankton
density and water flow• Oyster newly settled larvae (spat) collected and
then transferred to trays that are suspended from rafts
• Problem: bivalve diseases, e.g., MSX in oysters - amoeboid protozoan
![Page 38: Marine Fisheries and conservation of marine resources](https://reader033.vdocuments.net/reader033/viewer/2022061615/56815e6b550346895dccea7f/html5/thumbnails/38.jpg)
The End