Developments in managing small pelagic fisheries

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1 Developments in managing small pelagic fisheries Prof Ray Hilborn Your essential event for networking and information

2 Impacts of fishing forage fish on their predators: Progress report October 2017 Ray Hilborn School of Aquatic and Fishery Sciences

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4 Key conclusions of Pew Forage Fish Report > Adopt harvest strategies and management measures so that there is a greater than 95 percent chance that fishing on forage fish will not deplete any dependent predator population to levels that would meet the IUCN vulnerable criteria > This is used to formulate recommendations about specific harvest management actions

5 Information Level Recommended minimum biomass Recommended fishing mortality rate High Greater than 30% unfished biomass Less than 0.75 FMSY Intermediate Greater than 40% unfished biomass ½ Natural mortality rate or ½ FMSY whichever is smaller Low No new forage fisheries Should not reduce population more than 20% below unfished biomass

6 The MSC report The MSC group found that the number of indirectly affected groups was generally small at moderate harvest rates (50% of Fmsy, corresponding to about 75% of Cmsy) but increased sharply thereafter in some ecosystems. The MSC study was used to develop new guidelines for assessing low trophic level fisheries under the MSC standard

7 These two reports are currently the major available studies on impacts of fishing forage fish > Our project seeks to advance the science by identifying what was missing from the previous analysis and providing more reliable guidance for managers

8 Basic biology missing from LENFEST and MSC analysis natural variability of forage fish stocks the extent of size overlap between fisheries and predators Both forage fish and predators were often lumped into groups No representation of how the spatial distribution of forage fish changed with abundance and density near breeding sites of predators would change.

9 Also totally missing from LENFEST and MSC report Empirical analysis of the relationship between forage fish abundance and population size or population change in predators That is they relied on theoretical models and not data If LENFEST is correct we should see predator populations decline at low prey abundance and increase at high prey abundance

10 Critiques of LENFEST report We find that the depth and breadth with which predator species are represented are commonly insufficient for evaluating sensitivities of predator populations to forage fish depletion.

11 Critiques of LENFEST report

12 Very different results from more detailed models constructed for examining impacts on predators They found a 1.8% difference in abundance of brown pelicans between unfished and fished populations of sardines and anchovy

13 What the Punt MICE model included > Natural variability of forage fish stocks > The extent of size overlap of forage fish consumed between fisheries and predators > Explicit representation of spatial structure, including localized depletion or natural variation in spatial ranges.

14 Our first paper

15 Key results of this paper > When you include natural variability in forage fish, the impact of fishing on predators is generally much less than caused by natural variability > Fishing generally has little impact on the recruitment of forage fish > There is little size overlap between many predators diet and the fishery thus less impact than if they overlapped > There appears to be little empirical relationship between forage fish abundance and predator rates of increase

16 Current work plan > Recruitment analysis > A generic MICE model that incorporate recruitment variability, and other missing elements > Application of the MICE model to several forage fisheries > Evaluate alternative harvest strategies for different systems > Expand data base on size distribution of forage fish, predators diets, and fishery selectivity > Empirical analysis of the relationship between forage fish abundance and their predators

17 Progress: Recruitment analysis > Paper submitted with key results: > Half of forage fish stocks show periodic regime shifts in productivity > For these stocks estimates of the impact of fishing on recruitment will be overestimated: what appears to be low recruitment at low spawning stock is really low spawning stock caused by low recruitment > In general forage fish recruitment curves show little relationship between abundance and recruitment

18 Progress: Generic MICE model > Completed and running for California Current and Peruvian Anchoveta > For California current we show little impact of fishing sardines or anchovy on Sea lions and pelicans

19 Bird numbers (millions) Peruvian anchoveta Observed and predicted total guano birds Year

20 Instantaneous mortality rate Peruvian anchoveta 4.5 Guano bird mortality rates during die-off events: severity of impact did not depend on anchoveta abundance Anchoveta biomass MMT

21 Progress: Optimal Harvest strategies > Initial results: > Nothing like the LENFEST proposals

22 Progress: Next steps > Submission of papers on Models of Peruvian anchoveta Harvest strategies Empirical relationship between forage fish abundance and predator trends > Further models of other forage fish systems

23 Phase II timeline > Recruitment analysis paper by summer > Conference call in June or July > Follow up meeting perhaps June 2017 when many participants will be in Seattle

24 Phase II timeline Overview > Recruitment analysis paper by summer > Conference call in June or July > Follow up meeting perhaps June 2017 when many participants will be in Seattle

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