Bycatch

Question 1

Target catch

Answer 1

Species or species complex that is the target of fishery

Question 2

Incidental catch

Answer 2

Non-target species that are retained (retention may be dependent on catch rate of target species)

Question 3

Bycatch

Answer 3

Catch that is not retained (returned to the sea – dead or alive)

Question 4

Bycatch may be….

Answer 4

Dead
Living at time of release
Survival depends on condition, barotrauma,
environmental factors

Question 5

Non-regulator discard driving factors

Answer 5

Non-target species of limited value
Target species that are damaged, diseased or too small for the market (e.g., cannery)

Question 6

regulator discard driving factors

Answer 6

Protected species
Size limit (minimum size, slot limit)
Closed season or area
Protected sex
Quota already filled
Retention limit (exceeds allowable fraction of target catch or bag limit)

Question 7

Global discards cut by ~50%+ 1980s–2010s
WHy?

Answer 7

Greater utilization of bycatch species (aquaculture feed)

More selective fishing methods

Decline in intensity of fishing for high discard-rate species (industrial fishing ↓)

Management measures prohibiting or limiting bycatch (time/area closures, limiting use of unselective gear, requiring use of bycatch reduction devices)

Question 8

Country-level mandates

Answer 8

EU landing obligation (no discards since 2019, though some exemptions)

Iceland, Norway, Namibia prohibit discarding

Question 9

What is another possibility associated with the decline in bycatch?

Answer 9

Possible that bycatch populations have decreased relative abundance

Question 10

What are ways to manage bycatch?

Answer 10

Limit overall effort (also reduces target catch)
Time/area closures
Bycatch reduction engineers
Incentivize selective fishing

Question 11

Time/area closures is related to

Answer 11

relative abundance of target species and bycatch species are spatially/temporally variable

Question 12

What does bycath reduction engineering require?

Answer 12

difference in biology (size, movement, behavior, etc.) between target and bycatch species

Question 13

U.S. Gulf of Mexico Shrimp

Answer 13

“Gulf shrimp” includes white, brown, and pink shrimp

Fishery operates using bottom trawls (twin otter trawls most common)

Economically important fishery → $300M+/yr

Abundance environmentally driven

Question 14

Bycatch in shrimp fishery

Answer 14

During 1990s, high bycatch rates became an increasing concern (bycatch made up ~84% of total catch by weight)

~90% of age 0 red snapper mortality due to shrimp bycatch

Question 15

Turtle Excluder Device (TED)

Answer 15

Early designs (‘88 – ‘03)
97% turtle exclusion
4% fish bycatch reduction
0-6% shrimp reduction

2021 NMFS requires TEDs be used in skimmer trawls >40ft

Question 16

Shrimp finfish bycatch

Answer 16

Much greater than target catch, large number of juveniles (some adult stocks overfished)

Bycatch reduction devices required since 1998 (several approved designs)

2005 red snapper assessment recommended a 74% reduction in shrimp trawl bycatch mortality → primary factor affecting stock recovery

Question 17

Alaska pollock

Answer 17

$300M+, 3B+ lb in annual landings (largest in US by volume)

Caught using mid-water trawls targeting schools

Question 18

Alaska pollock bycatch

Answer 18

Relatively low bycatch rate (~1% by weight); still substantial given magnitude of the fishery

Bycatch includes: halibut, herring, salmon

Question 19

Salmon bycatch with Alaska pollock

Answer 19

Trawl fisheries in Bering Sea and Gulf of Alaska associated with salmon bycatch (Chinook, chum)

Salmon are considered prohibited species in Alaskan groundfish fisheries (cannot be retained for sale)

Bycatch highly variable year-to-year

Question 20

Slamon bycatch managed how?

Answer 20

Prior to 2011, salmon bycatch managed via time-area closures

Fishery management plan amendments (2011, 2012, 2016) aimed at reducing salmon bycatch by incentivizing selective fishing behavior

Question 21

Incentive plan agreements (IPAs)

Answer 21

plans developed by each sector to penalize bycatch and reward clean fishing at the vessel level

Question 22

IPAs introduced into Salmon bycatch

Answer 22

Vessel bycatch allocations (similar to IFQ), including rewards/penalties based on bycatch avoidance
Insurance pools
Hotspot maps / increased fleet communication
Use of salmon excluding devices

Question 23

How are the IPAs working?

Answer 23

Chinook salmon bycatch down ~50% compared to 1991-2010; chum salmon bycatch increasing

Question 24

Eastern Pacific Tuna

Answer 24

Commercial fisheries since early 20th century targeting yellowfin, skipjack, and bigeye

Before 1960s, fishery was primarily pole-and-line vessels out of California using live bait and fishing coastal waters (clean fishery)

Purse seining began in 1960s/1970s

Question 25

Dolphin bycatch with Tuna fishery

Answer 25

Dolphins (spotted, spinner, & common) often associated with larger yellowfin tuna

Dolphins chased down with speed boats, purse seine set around dolphins and tuna

High mortality of dolphin caught in nets 1960s/1970s (difficult to estimate precisely)

Question 26

Dolphin bycatch public concern

Answer 26

beginning in late 1960s

Marine Mammal Protection Act of 1972 led to a mandatory observer program for US vessels
~33% of trips by 1977

Fishery expanded offshore, more countries fishing → IATTC involved

Question 27

“Dolphin Safe” Tuna

Answer 27

US canners refuse to purchase tuna caught using dolphin sets, leading to the creation of the “Dolphin Safe” label via the 1990 Dolphin Protection Consumer Information Act (16 USC 1385)

Question 28

Tradeoffs in tuna bycatch

Answer 28

Shift from dolphin sets to log/FAD sets reduces dolphin bycatch but increased bycatch of other species