Fish Conservation and

Management

CONS 486

Northern Atlantic Cod:

A management and conservation

failure

Chapter 12 Ross

Life history

• Mature at ~ 7 yrs

• > 30 yr max life

• Size at maturity: 50-100 cm (can be 2 m long!)

• Fecundity: 12 million eggs (compare to <10K for salmon!)

• Spawn on deep ocean shoals

Atlantic cod juvenile

Atlantic cod aggregations

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).

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’

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?

Fishing approaches primarily used in inshore fishery:

• Trapnets (the cod trap)

• Machine jigging

• Hook-and-line

• Longlines

• Gillnets

Fishing approaches primarily used in offshore fishery:

• Purse seines

• Trawling

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)

• Note large foreign catch prior to 200 mile limit, and

shift to offshore Canadian fishing

• Growth overfishing not detected by

research surveys but average size was

declining

• Same size decline in another commercial

species

Size and abundance declining in non-

commercial species - WHY?

-caused by ‘discarding’ and non-reporting of this by-catch

-consistent with numerous accounts of discarding small cod

- Predation by seals also suggested as a cause but their

numbers were not increasing proportionate to the rapid

cod decline

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.

• Recruitment overfishing of spawning stock!

• Recruitment overfishing of spawning stock!

Why did populations collapse?

How did this happen?

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

Are cod recovering?

• Maybe, but slow - why?

• Competition: niche occupied by others (e.g. skates,

rays)

• Climate change not helping (oceans getting warmer)

• Bottom trawling destroyed spawning habitats

Bring out yer dead!

But I’m not dead yet..

Sometimes its hard to know if you are

winning or losing the imperilment game!

Echograms of cod from the acoustic surveys. Seabed is indicated in dark red, vertical blocks span

1 nautical mile (1852 m), and horizontal blocks span 50 m. In all cases, cod are distributed >100 m

off the bottom.

(a) June 1990 - migrating and spawning cod

in the Bonavista Corridor

(b) March 2008 - The first observed

aggregation in the Bonavista Corridor since

1992

(c) May 2014 - spawning aggregation in the

Bonavista Corridor

(d) May 2015 - spawning aggregation in the

Notre Dame Channel

Biomass estimated from

echograms of cod and their main

food capelin from the acoustic

surveys.

-Since 2011, abundance continues to

increase.

-Increase in food availability is major

reason.

-Older fish in population also have

better condition than in recent past.

-All signs of recovery under way……

The main factors that kick-started

the increase appear to be capelin

abundance and perhaps

immigration of at least one strong

year-class, which occurred during

a period of favourable climate and low

removals through the

fishery.

Rose G.A. and Rowe S. 2015. Northern Cod Comeback. Can. J. Fish.

Aquat. Sci. Vol. 72, 2015

“The main factors that kick-started the increase appear to be capelin

abundance and perhaps immigration of at least one strong year-class,

which occurred during a period of favourable climate and low removals

through the fishery.”

“With continued growth in the capelin stock and frugal management (low

fishing mortality), this stock could rebuild, perhaps within less than a

decade, to historical levels of sustainable yield. More generally, if this

stock can recover, the potential exists for recovery of many other

depleted stocks worldwide.”

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

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

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

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 3

1995 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 6 1995, Fisheries Minister Tobin said he would arrest

any “pirate ships” fishing outside our EEZ on straddling stocks

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

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

Atlantic Striped

Bass:

A management

and conservation

success….

…finally!

Life history

• Mature at ~ 3 yrs, > 30 yr max life

• Fecundity ~ 1 million eggs

• Size at maturity ranges from 50-100 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

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?

Range (US)

Chesapeake Bay

• 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.

• 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.

• 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

Ability to take advantage of a lucky break!

Compliance with min size limits

• 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.

• this tactic caused an increase in CPUE, and an increase in catch per trip

so anglers were very happy!!

http://www.nefsc.noaa.gov/sos/spsyn/af/sbass/

Note the growth of the recreational fishery

What sequence of events turned the collapse around?

Atlantic States Marine Fisheries Commission (ASFMC – 13 states involved)- 1977 ASMFC developed plan - not all states bought in

• Pressure from commercial sector• Stocks continue to decline…

- 1981 min size limits (14” in bays and 24” along coast) and area closures• Resistance, continued decline..

- 1984 federal passage of Striped Bass Act• State govs can normally do what they want with fisheries but threat of federal

penalties = compliance

- 1984/1985 moratorium placed on 1982 age class• Strong class that needed protection• Annual increases in minimum size limit protect ‘8s class

- 1995 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

Beverton-Holt

Stock-Recruit relationships

• More science!

Ricker

• 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.

Scientific surveys also included ocean trawls

• Now managers can respond quickly to reduce harvest if warranted

Why did populations recover?

Why did populations recover?