Fisheries Management – The Practice Stock Assessment

INPUTS: Effort (fishing vessels, fishing hours)

FISHING

OUTPUTS: Size / Age Catch Biomass CPUE Fishing Mortality Fishery Management

INPUTS: Effort (& Technology) (Gas, Bait, Gear, Subsidies)

FISHING

Bycatch

Habitat Impacts

OUTPUTS: Fish Jobs, Profits Externalities Are Sustainable Fisheries Achievable ?

(Chapter 15 - Hilborn 2005) Other Aspects of Sustainability: Economic Basis / Social Basis

Economic Social

- Resource Ownership - Management Institutions (property rights / traditions) (assessment, enforcement)

- Subsidies (gas / ice) - Pride / Ownership Principle 1. MSY curve Result: Management Implications: MSY occurs at B = K / 2 - Monitor B and vary catches accordingly

- B msy: Maintain B at K/2

- F msy: Regulate Fishing

Mortality (% B)

(dN / dt) / (dN Population Change Change Population

0 K / 2 K Population Size (Biomass) Spawner – Recruit Relationships The working conceptual model for Bering Sea walleye pollock is a survival gauntlet model representing the successive conditions or switches that must be realized for the fish to survive.

Each switch has a conditional probability for survival. The probability is subject to spatial and temporal variability in physical / biological conditions... and may be density-dependent. Switch Model

(Quinn and Niebauer 1995) Switch Model Density-dependent and Density-independent Factors:

The “feeding larval switch" is dependent on water temperature, which varies in space and time. Switch acts on individuals (density-dependent) and entire cohorts (density-independent) (e.g., Starvation).

The “juvenile survivorship switch” is influenced by density dependent factors related to both the abundance of the juvenile and the adult fish (e.g., Cannibalism) Spawner – Recruit Relationship Conceptual Model of the Relationships Between Pollock Recruitment and Biophysical Correlates in Southeast Bering Sea

Moderate density dependence between the spawning stock biomass and the recruitment, with reduced recruit survival at high adult abundance

Spawner – recruit curve suggests other driving mechanisms because several points are well above and below the fitted relationship.

Points way above the line (Bailey et al. 1996) (1978, 1982, 1989) are warm-water years Marine Population Dynamics

(Chapter 4 – Levitan and McGovern 2005)

The Allee Effect:

“Decreases in population density result in decreased per capita population growth”

Specially Exciting Examples: Broadcast Spawning (Density) –>

Nursery Habitats (Cues / Refuges) –> Urchins White Abalone ( sorenseni) Allee Effect Once occurring in high densities (1 per m square of suitable habitat), recent surveys show densities of 1-3 per hectare (10000 square m) in historical core (NMFS) habitat (Channel Islands)

White Abalone Restoration: On 2001, biologists placed 3 F and 2 M in separate containers in the lab and added hydrogen peroxide. Two hours later, 2 females spawned about 3 million eggs, followed by release of sperm from one male. Biologists mixed the eggs and sperm and obtained a 95 percent fertilization rate. White Abalone - Harvesting and Decline

Surveys in Southern California show a 99% reduction in density of white abalone since 1970s

(Rogers-Bennett et al. 2002) White Abalone - Recovery Project

Populations significantly declined in 1970s as the result of commercial fishing and in 2001 became first marine invertebrate to be listed as an endangered . A recovery plan was developed by NOAA NMFS.

Recovery steps:

• prevent harvest, protect habitat, and survey wild populations • propagate species in captivity with goal of outplanting larvae, juveniles, and adults into their native range

Captive propagation hindered by high mortality from bacterial withering syndrome. Allee Effect Below minimum abundance threshold:

• There is no recruitment • Population declines Threshold

Important in group living , such as schooling fishes. It may cause a

population to collapse if Recruitment harvesting pressure is too strong, as has happened for 0 T K some pelagic fisheries. Population Size (Biomass) (Courchamp et al. 1999) Principle 2. CPUE proportional to Biomass In some instances, CPUE is not a good metric of Biomass

CPUE f (B, E)

Catch (Time T) (Time Catch 0 High 0

0 High Population Size (Time T) Limitations of CPUE Other inputs go into fishery, and influence the ability to catch fish:

- Vessel size - Other Technologies: - Vessel Type spotter planes, satellites (processors)

- Depth finders - Thermistors - Fish finders Limitations In some instances, CPUE is not a good metric of Biomass

Example: Stocks with high degree of aggregation Fish density: 1 per sq km

In normal year: Stock: 30 Area: 30

Catch 10 Effort 10 CPUE = 1 Limitations In some instances, CPUE is not a good metric of Biomass

Example: Stocks with high degree of aggregation Fish density: 2 per sq km

In restricted habitat year: Stock: 30 Area: 15

Catch 20 Effort 10 CPUE = 2 Limitations In some instances, CPUE is not a good metric of Biomass

Example: Stocks with high degree of aggregation Fish density: 0.5 per sq km

In expanded habitat year: Stock: 30 Area: 60

Catch 5 Effort 10 CPUE = 0.5 Limitations In some instances, CPUE is not a good metric of Biomass

Example: Stocks with high degree of aggregation Fish density: 1.5 per sq km

In poor year: Stock: 15 Area: 10

Catch 15 Effort 10 CPUE = 1.5 Limitations In some instances, CPUE is not a good metric of Biomass

Example: Stocks with very restricted range / low motility Limitations Year 1: Catch 10, Effort 10 CPUE = 1 B = 25 Limitations Year 2: Catch 10, Effort 10 CPUE = 1 B = 15 Limitations Year 3: Catch 5, Effort 10 CPUE = 0.5 B = 5 Limitations Year 4: Catch 0, Effort 10 CPUE = 0 B = 0 A seamount is an independent submarine mountain rising from seafloor to at least 1,000 m above the seafloor.

There are over 100,000 seamounts worldwide. Shallow seamounts (height: 1000 – 3000 m) marked in red, deeper seamounts are in blue. © Seung-Sep Kim / Chungnam National University Depending on the depth of the summit, seamounts can interact with epi / meso – pelagic fish and species. Is this a Realistic Scenario? Trawling on Seamounts: Pitcher et al. 2010

Technological advances have deepened trawling impacts Why Such a Slow Recovery ?

Habitat Destruction Population Dynamics Are Sustainable Fisheries Achievable ?

(Chapter 15 - Hilborn 2005)

Types of Biological Traits that Support Sustainable Fishing: Low Vulnerability / High Recovery Vulnerability Rapid Population Growth

- Size: Maturity vs Recruitment - Fecundity

- Behavior: Schooling / Aggregation - Longevity (Age Maturity)

- Refugia: MPAs / habitat Marine scientists Make Call For Seamount Closures For Research

Morato et al. 2010 Global Fisheries & Marine Conservation: Is Coexistance Possible? (Chapter 11 - Preikshot & Pauly 2005)

Injecting conservation- oriented thinking into fisheries management implies strong emphasis on no-take MPAs.

MPAs can buffer exploited populations from effects of environmental variation. Global Fisheries & Marine Conservation: Is Coexistance Possible? (Chapter 11 - Preikshot & Pauly 2005)

The socio-economical and ecological implications / impacts of fishing depend on the “scale” of the fisheries 3. Other Unwanted Consequences

The definition of bycatch, as stated in Magnuson-Stevens Fishery Conservation and Management Act:

NOAA Fisheries uses the following definition for its National Bycatch Strategy and bycatch reduction efforts:

Two Approaches to Marine Conservation

(Rolf & Zacharias 2011) Traditional: Novel: - Species Focus - Ecosystem Focus

- Single species - Multi-species

- Fishery controls - Managing spaces References

Bailey, K.M., R.D. Brodeur, and A.B. Hollowed. 1996. Cohort survival patterns of walleye pollock (Theragra chalcogramma) in Shelikof Strait, Alaska: A critical factor analysis. Fish. Oceanogr. 5 (Suppl. 1): 179-188.

Quinn, T.J., II. and H.J. Niebauer. 1995. Relation of eastern Bering Sea walleye pollock (Theragra chalcogramma) recruitment to environmental and oceanographic variables. pp. 497-507. In: Beamish, R.J. [ed], Climate Change and Northern Fish Populations, Can. Spec. Publ. Fish. Aquat. Sci. 121, 739p.

Courchamp, F., Clutton-Brock, T., and Grenfell, B. 1999. Inverse Density Dependence and the Allee Effect Trends in Ecology & Evolution 14(10): 405-410. North Atlantic Swordfish

http://firms.fao.org/ firms/resource/10023/

Evidence of Shifting Baselines? The average North Atlantic swordfish caught in the 1960s weighed 300 pounds. By the late 1990s, the average was 100 pounds (NOAA - ICCAT). History of Swordfish Fishery

1920s – Recreational fishery begins, primarily from Massachusetts to New York

1960s – Longline gear introduced in commercial fishery, replaces harpoons

1966 – International Convention for Conservation of Atlantic Tunas signed creating International Commission for Conservation of Atlantic Tunas (ICCAT)

1970s – Recreational fishery develops in Florida 1990 – ICCAT passes first recommendation on swordfish, calling for harvest reductions of undersized North Atlantic swordfish 1999 – ICCAT establishes 10-year rebuilding program Managing Sliding Fisheries

Empirical Observations Modelling Efforts

Catch Data Fishery Surveys (logbooks / observers) Stock-Recruitment Data ((NOAA Fisheries) Recent History of Swordfish Management

2000/2001 – NOAA Fisheries implements several large time and area closures for pelagic longline fishing to reduce bycatch of juvenile swordfish and billfish

2002 – Stock assessment determines stock biomass is 94 % of

level needed for maximum sustainable yield (BMSY)

2004 – NOAA Fisheries Service implements bycatch reduction measures in commercial fishery (Goal: reduce take of small-size fish)

2006 – Stock assessment estimates that biomass approximately 99 % of BMSY 2007 – U.S. regulations establish baseline quotas and develop methods for catch reporting of recreational fishers (Goal: do not overshoot the quota)

2009 – North Atlantic swordfish is considered fully rebuilt Managing Sliding Fisheries

Empirical Observations Modelling Efforts

Catch Data Fishery Surveys (logbooks / observers) Stock-Recruitment Data ((NOAA Fisheries) Swordfish Boycott

Is there a problem? Swordfish stocks in trouble - starting in late 1990s.

What actions were taken? U.S. NMFS set fishing limits, while conservation groups organized swordfish boycott by chefs and restaurants in 1998.

Did they succeed? Boycotters claimed victory, claiming it showed the power of market forces, but fisheries managers disagree, saying recovery was response to actions implemented years before the boycott. Swordfish Catch

2017SWO ATL Stock Assessment www.iccat.int/Documents/Meetings/Docs/2017_ATL_SWO_ASS_REP_ENG.pdf Abundance and Fishing Mortality

B: Biomass F: Fishing Mortality (0 to 1) (combined weight of fish in population)

SCRS/2009/016 - SWO ATL Stock Assessment www.iccat.int/Documents/Meetings/Docs/2009_SWO_ASSESS_ENG.pdf Swordfish Status

Red Box: Stock is overfished and Yellow #1 being overfished Green Box: Stock is not overfished and not being overfished

Yellow What is going on in the #2 two yellow boxes?

2017SWO ATL Stock Assessment www.iccat.int/Documents/Meetings/Docs/2017_ATL_SWO_ASS_REP_ENG.pdf References

FAO's report "Review of the State of World Marine Fisheries Resources", tables D1-D17, ftp://ftp.fao.org/docrep/fao/007/y5852e/Y5852E23.pdf

http://www.nmfs.noaa.gov/sfa/statusoffisheries/