Fishing down Canadian aquatic food webs

The mean trophic level (TL) of fish landed in fisheries on the east and west coasts of Canada is declining by 0.03–0.10·decade–1, similar to global trends. This finding is based on data from United Nations Food and Agriculture Organization and the Canadian Department of Fisheries and Oceans and other Canadian sources for the period 1873–1997. Significant rates of decline in mean TL were obtained even when key species — Atlantic cod (Gadus morhua) on the east coast and Pacific herring (Clupea pallasi) and Pacific hake (Merluccius productus) on the west coast — were omitted from the analysis. Fish taken in inland water fisheries did not exhibit a decline in mean TL. Two models were developed, based on length and age, respectively, for correcting TL estimates of individual species for the effects of changes in body size due to changes in fishing mortality. Both produced corrections that were small relative to changes in mean TL that resulted from changes in species composition of the catch over time. Overall, these results suggest that the mean TL of fish landed can be used as an index of sustainability in ultispecies fisheries and that its reliability will depend on the quality of the data and length of the time series available for analysis

Fisheries Centre research reports, Vol. 6, no. 5

The contributions in this report jointly describe the ecosystem of the Strait of Georgia, British Columbia, Canada, as it presently is, and as it might have been one hundred years ago, before the massive expansion of commercial fisheries, and five hundred years ago, before contact of native Peoples with Europeans. The evidence reviewed includes ecological studies and analyses not only from all of the fish species, but also from all parts of the ecosystem, from whales, seabirds and salmon, to plankton, herring and clams. Essential information on the presence, location and abundance of living organisms is obtained from historical records and documents, linguistic studies, archaeological remains (including petroglyphs and pictographs), and the oral history and traditional environmental knowledge of the Aboriginal people who still live around the Strait of Georgia. All of the scientific and cultural information is used in the “Back to the Future” method. This qualitative and quantitative evidence, gathered during a three-month pilot project, was reviewed at a multidisciplinary workshop held in November 1997 at the First Nations House of Learning, U.B.C. The data has been used to construct ECOPATH mass-balance models of the Strait of Georgia for the three time periods. The models comprise 25-27 functional groups. The epistomological, conceptual, and methodological issues raised by this interdisciplinary approach are discussed, as is the suitability of the ECOPATH method to serve as a template for ecosystem reconstructions of this type. The work reported here represents a pilot phase in developing this new methodology. The “Back to the Future” process includes the model reconstruction of past and present ecosystems as a way of informing policy choices for fisheries. The evaluation of local benefits that may be extracted from alternative ecosystems, the design of practical management instruments, and the monitoring of the recovery of ecosystems and compliance, are all factors all that may endow the “Back to the Future” method with powerful support and consent among an unprecedented broad range of stakeholders. The next steps, both for improving the Strait of Georgia reconstructions and for the “Back to the Future” methodology, are discussed.Science, Faculty ofOther UBCNon UBCOceans and Fisheries, Institute for theUnreviewedFacultyGraduat

Early marine survival of coho salmon in the Strait of Georgia declines to very low Comparison of techniques for correlating survival and gene expression data levels

Abstract.-The marine survival of juvenile coho salmon Oncorhynchus kisutch from the time they enter the Strait of Georgia in mid-May to the time of our trawl survey in mid-September declined from an average of about 15% in 1998 to approximately 1% in 2007. Early marine survival rates for juvenile coho salmon have been consistently low (,5%) since 2002, and the rate of decline in early marine survival was greater for hatchery fish than for wild fish. This suggests that hatchery coho salmon are perhaps less able to survive than wild fish in the current marine ecosystem. The steady decline in total marine survival for coho salmon over the past four decades coincided with a warming of the Strait of Georgia, where both sea surface and sea bottom temperatures have increased by approximately 18C since 1970. Another factor that appears to have contributed to the decline in early marine survival since the late 1990s is an increase in the number of days with an average sustained wind strength greater than 25 km/h. The linkage between wind strength and marine survival requires further study, but wind strength is known to affect the timing and level of primary productivity. The processes that caused the declining marine survival remain to be identified and may include factors associated with disease originating in both freshwater and salt water, metabolic stress, competition, and predation. The data suggest that coho salmon brood year strength is now mostly determined during the first 4 months spent in the Strait of Georgia. If the current low levels of marine survival continue, management initiatives to protect wild coho salmon will be urgently required, and it will be timely to critically evaluate the hatchery programs and policies

Fisheries Centre research reports, Vol. 15, no. 1

DIRECTOR'S FORWARD. EXECUTIVE SUMMARY. 1. Introduction. 2 Comprehensive catch as a pre-requisite to ecosystem-based management. 2.1. Problem statement, with emphasis on BC. 2.2. Methods for estimating unreported catches. 2.3. Native fishery and First Nations footprint at European contact. 3. Ecosystem modelling. 3.1. Ecopath with Ecosim. 3.2. Ecosystem delineation. 3.3 Available models of the northeast Pacific. 3.4. Questions that have been addressed. 4. Rebuilding value and Back To The Future approach. 4.1. Local and traditional environmental knowledge. 4.2. Models developed. 4.3. Including long-term climate. 4.4. Fleet dynamics. 4.5. Policy search. 5. Ecosystem status. 6. Socio-economic models. 6.1. Valuations of 'goods and services' from the marine environment. 6.2. Socio-economic models of resource use. 6.3. BC case studies of valuation. 7. Conclusion. ACKNOWLEDGEMENTS. REFERENCES.Fisheries Centre (FC)UnreviewedFacultyResearcherGraduat

Fisheries Centre research reports, Vol. 6, no. 6

DIRECTOR'S FOREWORD -- ABSTRACT -- TABLE OF CONTENTS -- LIST OF EXHIBITS -- ACRONYMS AND ABBREVIATIONS -- 1. INTRODUCTION (Ramon Bonfil et al.) • Project Direction and Management -- 2. METHODOLOGY (Ramon Bonfil et al.) -- • Overall Strategy -- • Ecological and Economic Modelling -- • Rapid Appraisal of Fisheries Sustainability -- 3. A GLOBAL OVERVIEW -- • Fishing Patterns of DWFs 1950-1994 (RamonBonfil) -- • Selected Case Studies of DWFs (Ramon Bonfil) -- • Case Study: DWFs off Mauritania and Senegal (Ramon Bonfil) -- • Ecosystem -- • The DWF Nations -- • The Fishery Resources and Fishing Sectors -- • Historical Catches -- • Catches of the DWF -- • Fleet Characteristics and Numbers -- • Fisheries Management by Coastal States -- • Bycatch -- • Fishing Agreements -- • Benefits -- • Conflicts -- • Boxed Case Study 1. Illegal Fishing in the Galapagos Islands {Ramon Bonfil et al.) -- • Case Study: Walleye Pollock and the North Pacific "Donut Hole" (Ramon Bonfil) -- • Ecosystem -- • The DWF Nations -- • The Fishery Resources -- • Historical Catches -- • Fleet Characteristics and Numbers -- • Fisheries Management -- • Bycatch -- • Fishing Agreements -- • Benefits -- • Conflicts --Fisheries Centre (FC)UnreviewedFacultyResearcherPostdoctoralGraduat