Bycatch &discards

Faculty of fish resources Suez university – Egypt

Prepared By ;Salma Ibrahim Baghdady

Overview :• introduction• The mean of bycatch & discards• environmental & social Impacts• Some strategies & solutions• Some bycatch reduction devises in shrimp trawls :TEDsJTEDsRESSquare mesh codendsFisheyesSquare mesh window • Relation between effort & bycatch• Effects of cod-end mesh size on the catch discarded

Introduction:• Many fisheries are non-selective fishing

gear catching animals that they did not intend to. This non-taget extra catch is known as ‘bycatch’.

• Of these bycatch species, some have a commercial value and are brought back to land by fishers to be sold. However, a large proportion is unwanted and so is discarded-thrown back over the side of the boat.

FAO estimates:7.3 million tonnes of fish is discarded every year

• Nearly 20 percent of shark species are threatened with extinction, primarily as a result of being caught accidentally on longlines. Bycatch also includes young fish that could rebuild populations if they were allowed to grow and breed.

Hundreds of thousands of sea turtles, seabirds and marine mammals, including whales, dolphins and porpoises, die as bycatch. As many as 200,000 loggerhead sea turtles and 50,000 leatherback sea turtles are caught annually. Longline fishing also kills hundreds of thousands of seabirds when they become entangled in drift nets or caught on longline hooks when they dive for bait.

This black-browed albatross has been hooked on a long-line.

Seabirds with longline fishing vessel

Not only fish:

By catch is the portion of the catch that is not comprised of the fishery’s target species .Species that are caught accidentally

Bycatch from a shrimp trawler

The FAO defines discards as the portion of the catch that is thrown back into the sea either dead or alive . Like marine mammals , crustaceans , and seabirds ,sharks, birds, turtles, corals ,etc.

catch

Target species Valuable

bycatch

• Non valuable species

• Over quota species

• Undersized individuals

market Discarded

Bycatch from shrimp trawling usually consistsof many fish species and occasionally largeanimals.

Results;

• Waste of a natural resource without any economic returns.

• Major threat to the health of fish stocks• Threat to the future of the fishing industry• Capture and discarding juvenile lower catch

opportunities for those species in the future

-Negative impact on the marine ecosystem & biodiversity

-Decrease The sustainability of fisheries

Bycatch also includes sponges and rocks andmay reduce the quality of the shrimp catch.

Solution:• Use and development of species selective gear.• Monitoring and control of fishing gears• Motivating Technical conservation measures to improve

gear selectivity.• Use Electronic logbooks (assessing discard rates during

routine inspection by fishery inspectorate officers. )• The use of closed areas or protected areas to protect

juvenile and spawning fish.• fisheries management &marketing strategies • State’s laws for prohibiting discards & overgrading.

Sustainable development

fishermen have been using fishing methods designed to reduce the capture of many of these animals, including:

• ground chain arrangements that reduce theamount of seabed animals, rocks and debris taken,

• avoidance of fishing grounds where bycatch isknown to be high, including grounds where coral, sponges and rocks are present,

• using mesh sizes big enough to allow somesmall animals to escape

• using TEDs and BRDs.

The first steps toward reducing bycatch is to identify the type of bycatch to be excluded

TEDsused to exclude turtles and other large animals from the trawl.

'turtle excluder device' is any modification to a shrimp trawl designed to reduce the capture of turtles. These devices are sometimes called a 'trawl efficiency device' because they can also prevent the capture of other large animals including sharks, stingrays, jellyfish and some large fish.

JTED• Juvenile and Trash Excluder Device

filters small fish including trash fish from the catch but not the larger shrimp

RES Radial Escape Section

BRD features a guiding funnel to concentrate all animals into the middle of the codend. As fish exit the funnel, some swim forward and through a panel of large square-meshes that extend radially around the codend

square-mesh codendssquare-mesh netting stays open for the duration of the tow, unlike diamond-mesh netting that closes under the weight of the catch. The selection of mesh size is very important and trial and error is needed to find the mesh size that maximises fish exclusion

T90:

fisheye• is designed to allow strong swimming fish to

escape from the trawl.

square-meshwindow

is simply a panel of large meshes hung on the bar so they remain open during the tow .This is in contrast to diamond meshes which tend to close under tension.

Relation between effort & bycatch:

Effects of cod-end mesh size on the proportion of trawl catch discarded

A key to the successful involvement of fishermen isto explore how they may benefit from reducing bycatch.

These benefits may include:

1. improved trawling and pocessing efficiency,

2. better product quality and marketing opportunities, and3. protecting the marine environment and extending the life of the fishery.

Longer trawl duration & wingend spread

Reduce damage to

codend

Quicker processing & sorting time

Reduce injures to crew from dangerous

animals

The catch on the right includes large animals because a TED was not fitted to the trawl.The catch on the left is the result of using a TED.

Discard weight* by major world region. Source: NRC bycatch database.

The top weight-based discard to landed target catch ratios by gear type :

References: • http://www.worldwildlife.org/threats/bycatch• http://

oceana.org/en/our-work/promote-responsible-fishing/bycatch/overview• http://www.fao.org/docrep/w6602e/w6602e09.htm• http://www.seafoodwatch.org/ocean-issues/wild-seafood/bycatch• http://en.wikipedia.org/wiki/Bycatch• A guide to bycatch reduction in tropical shrimp• MCS information sheet on discards and bycatch• https://www.youtube.com/watch?v=w_Nogi4E35I• https://www.youtube.com/watch?v=lbSQhy0axH0• https://www.youtube.com/watch?v=gwe06aoOE9g• http://www.fao.org/docrep/003/t4890e/T4890E03.htm#fig3• http://www.fao.org/docrep/003/t4890e/T4890E00.htm#TOC• https://www.youtube.com/watch?v=-pmv0Wm43MM