Fish Conservation and Management

Transcription

1 Fish Conservation and Management CONS 486 Northern Atlantic Cod: A management and conservation failure Chapter 12 Ross

2 What do Vikings have to do with this?

3 Life history Mature at ~ 7 yrs > 30 yr max life Size at maturity: cm (can be 2 m long!) Fecundity: 12 million eggs (compare to <10K for salmon!) Spawn on deep ocean shoals

4 Atlantic cod juvenile

5 Atlantic cod aggregations

6 Cod fisheries: rich in history the largest of its kind in the world was responsible for attracting Vikings and Basques (1000 years ago, Basques fished for 400 years before other nations) 1600s cod attracted French and British settlers to North America (founding Canada) when Britain won control of the Atlantic maritime area after the Battle of Trafalgar cod made them the world power and empire (why?) salted cod was the main dried food for use on ocean military ships and was a major trading commodity (for slaves, rum, sugar).

7 Cod fisheries: rich in history During the early to mid 1900 s, the cod fishery was the most important economic and social component of Atlantic Canada arguably the resource most responsible and influential for the founding and development of Canada in early 1960 s ~ 1-5 million tonnes of fish harvested per year In Cod we Trust

8 Cod fisheries: rich in history since 1992, fishery has been closed except for small localized fisheries In 2007, NFLD/Labrador stock listed as endangered by COSEWIC Other cod stocks listed as threatened or special concern Why the collapse?

9 Fishing approaches primarily used in inshore fishery: Trapnets (the cod trap) Machine jigging Hook-and-line Longlines Gillnets

10 Fishing approaches primarily used in offshore fishery: Purse seines Trawling

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12 Commercial catch data > 800,000 t peak harvest in 1968 Declined steadily to a low of 140,000 t in 1978 Suggests growth overfishing occurring BUT increased to 240,000 t in 1980s Collapsed in early 90s (resultant moratorium)

13 Note large foreign catch prior to 200 mile limit, and shift to offshore Canadian fishing

14 Growth overfishing not detected by research surveys but average size was declining

15 Same size decline in another commercial species

16 Size and abundance declining in noncommercial species - WHY?

17 -caused by discarding and non-reporting of this by-catch -consistent with numerous accounts of discarding small cod

18 - Predation by seals also suggested as a cause but their numbers were not increasing proportionate to the rapid cod decline

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20 More and more fish plants were built with funding from the federal govt who also funded heavily in fleet development, despite declining biomass of capture.

21 Recruitment overfishing of spawning stock!

22 Recruitment overfishing of spawning stock!

23 Why did populations collapse? - growth and recruitment overfishing How did this happen? - tragedy of the commons, over-capitalization, ratchet effect - cod fishery was used as the primary social/economic activity - political unwillingness to address the problems (catering to industry) - short-time series of scientific data, commercial catch data equally influential - unwillingness to deal with uncertainty in scientific abundance estimates - poor management use of data and poor advice to minister - very similar set of events led to the collapse of the US groundfish fishery just south of the border around the same time (read Chapter 12)

24 Role of Fish Behaviour 1980s: abundance didn t change much, why? Abundance estimated from fisheries catch surveys Abundance appeared higher due to behaviour! 1990s: new hydro-acoustic technology used to assess abundance Revealed cod moving (southward and offshore) into areas where the surveys and offshore fisheries were occurring!! Cod aggregations were concentrating Fisheries yielded consistent catches Surveys likewise affected

25 Are cod recovering? No! But why? Competition: niche occupied by others (e.g. skates, rays) Climate change not helping Bottom trawling destroyed spawning habitats

26 What have we learned from the cod collapse? Applied fisheries research: Don t use commercial catch data to estimate stock sizes Research surveys now include acoustics which enables better description of stock aggregations and movements Onboard observers, video surveillance of catch

27 What have we learned from the cod collapse? Management strategies: Reduce and don t encourage further capitalization Use risk-averse management decisions Precautionary approach, integrated mgmt. Do not harvest fish on spawning grounds i.e., protect spawning grounds

28 What have we learned from the cod collapse? Advisory councils: East Coast Conservation Council: industry and govt reps who examine data and advise Fisheries Minister Integrated Management: Transparent process for the public and enables industry to buy-in to decision

29 Epilogue to the cod collapse: The Turbot War -in 1994, Federal Coastal Fisheries Protection Act was passed which among other things states that Canada has jurisdictional rights to straddling stocks, countries that we had a current NAFO dispute with (Spain, Portugal) were exempt, but March it was amended to include these countries. -in past, disagreements over straddling stocks were an issue for the World Court, but Canada bypassed this with the Act, which set the stage for Turbot War -March , Fisheries Minister Tobin said he would arrest any pirate ships fishing outside our EEZ on straddling stocks

30 The Turbot War -on March 9, the Spanish fishing vessel Estai was fired upon by DFO -DFO/Coast Guard boats were cutting trawl nets off of fishing boats if they weren t allowed to board -on March 10 Spanish warships were sent to protect their interests -on April 16 we came within 20 minutes of all out war

31 The Turbot War -Canadian Destroyers ordered to sink any Spanish warship that removed their gun covers -Spanish fighter jets were making plans for refuelling in mid-air over their Falklands -bad weather saved the day and kept the Spanish fishing fleets away from the Canadian vessels -the following day Spain agreed to NAFO suggested conservation measures including observers on their boats and Canadian inspections, in return they got an increase in that year s quota of some species

32 Atlantic Striped Bass: A management and conservation success. finally!

33 Life history Mature at ~ 3 yrs, > 30 yr max life Fecundity ~ 1 million eggs Size at maturity ranges from cm Anadromous, spawning in rivers, rearing in estuaries and coastal areas along the New England and Carolinian coasts Many similar attributes to cod: life span, fecundity, size, but differ with much early age at maturation and are anadromous

34 History Since 1700s, important commercial species on East coast Recreational species since early 1980 s Hook and line gear predominates in both fisheries In 1972, US commercial landings peaked ~ 6000 tons then dramatically collapsed In Canada: St. Lawrence Estuary population is extinct Bay of Fundy and Gulf of St. Lawrence populations threatened In 1995, US stocks were declared recovered! Why did US pops collapse and recover?

35 Range (US) Chesapeake Bay

36 Declining abundance of outmigrating smolts to the ocean in Maryland and commercial landings both showing similar patterns (large declines from early 70s to early 90s) The science survey data are of good quality, and have been collected for decades prior to the decline. Poor juvenile survival was a result of lower number of returning adults and freshwater habitat problems.

37 Female abundance from spawning grounds showing reduced numbers starting in mid 70s reaching low point in mid 80s. The long term dataset enabled managers to determine what historical levels probably should be, thus could set a restoration goal. This goal was important as part of the restoration/recovery plan for the species.

38 Ability to take advantage of a lucky break! in 1982, by chance, a modestly abundant 8 year group appeared on spawning grounds the management system immediately protected those potential spawners through min-size limits 3-4 years later, their babies arrived on spawning grounds and those young to mid age classes started to be seen every year

39 Compliance with min size limits this tactic caused an increase in CPUE, and an increase in catch per trip so anglers were very happy!! recreational fishers complied with the min size limits imposed on the 1982 age class and started releasing a lot more fish to the point that almost all were being released by early 90s.

40 Note the growth of the recreational fishery

41 What sequence of events turned the collapse around? Atlantic States Marine Fisheries Commission (ASFMC 13 states involved) ASMFC developed plan - not all states bought in Pressure from commercial sector Stocks continue to decline min size limits (14 in bays and 24 along coast) and area closures Resistance, continued decline federal passage of Striped Bass Act State govs can normally do what they want with fisheries but threat of federal penalties = compliance /1985 moratorium placed on 1982 age class Strong class that needed protection Annual increases in minimum size limit protect 8s class juveniles back to levels they were at in late 60 s ASMFC wants to decrease minimum size which is now at 36 down to 28 but anglers want it to stay! Example of user groups engaged in conservation

42 Stock-Recruit relationships More science! Beverton-Holt Ricker

43 Scientific spawning ground data used to show trends and help managers set thresholds of recovery and upper end targets, anything above the SSB target is surplus for harvesting. The ability to set reference points using scientific data, models, etc is important and unique.

44 Scientific surveys also included ocean trawls Now managers can respond quickly to reduce harvest if warranted

45 Why did populations recover? Fisheries science Good long-term scientific assessment data on freshwater juvenile numbers and adult spawners Anadromous so getting data on spawners, juveniles much easier than cod (like salmon) in addition to Also spawning surveys and recent ocean surveys Life history Have relatively short generation times (unlike cod) and high fecundity Luck!! The occurrence of a strong year class (1982) coupled with Striped Bass Act passing just in time

46 Why did populations recover? Fisheries Management Decisions Timely management actions Size limits, closures, moratoriums, rearing habitat improvement Had recovery target Federal legislation with strong sanctions Interstate issues sometimes need federal solution Public and agencies both wanted to be risk-averse Some freshwater habitat issues were being addressed Unlike cod spawning areas Recreational fishery enabled min size limits They bought into the conservation actions Hook & line not damaging spawning habitats (or other species), like with cod No fishing on spawners