The use of ecological,fishing and environmental indicators in support of decision making in southern Benguela fisheries
Institution:
1. Marine Research (MA-RE) Institute and Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa;2. Statistics in Ecology, Environment and Conservation (SEEC), University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa;1. CSIRO Oceans and Atmosphere Flagship, Castray Esplanade, Hobart 7001, TAS, Australia;2. CSIRO Oceans and Atmosphere Flagship, GPO Box 2583, Brisbane 4001, QLD, Australia;3. Institute of Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point 7004, TAS, Australia;1. Fisheries Resource Harvest and Post Harvest Management Division, Central Institute of Fisheries Education, Fisheries University Road, 7-Bunglows, Versova, Andheri (W), Mumbai 400061, Maharashtra, India;2. Fisheries Economics Extension and Statistics, Division, Central Institute of Fisheries Education, Fisheries University Road, 7-Bunglows, Versova, Andheri (W), Mumbai 400061, Maharashtra, India;3. Department of Aquaculture, College of Fisheries, Mangalore 575002, Karnataka, India;1. Ocean Acidification Program, Office of Oceanic and Atmospheric Research and Office of Science and Technology, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1315 East-West Highway, Silver Spring, MD 20910, USA;2. Office of Science and Technology, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1315 East-West Highway, Silver Spring, MD 20910, USA;3. National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 166 Water Street, Woods Hole, MA 02543, USA;4. Office of Sustainable Fisheries, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1315 East-West Highway, Silver Spring, MD 20910, USA;5. Pacific Islands Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1845 Wasp Boulevard, Building 176, Honolulu, HI 96818, USA;6. Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 28 Tarzwell Drive, Narragansett, RI 02882, USA;7. Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way NE, Seattle, WA 98115, USA;8. Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 110 Shaffer Road, Santa Cruz, CA 95060, USA;9. Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 8901 La Jolla Shores Drive, La Jolla, CA 92037, USA;10. Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E, Seattle, WA 98115, USA;11. Office of Aquaculture, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1315 East-West Highway, Silver Spring, MD 20910, USA;12. Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, c/o Geophysical Fluid Dynamics Laboratory, 201 Forrestal Road, Princeton University Forrestal Campus, Princeton, NJ 08540, USA;13. Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 17109 Point Lena Loop Road, Juneau, AK 99801, USA;14. Office of Protected Resources, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1315 East-West Highway, Silver Spring, MD 20910, USA;15. West Coast Region, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1201 Northeast Lloyd Boulevard, Portland, OR 97232, USA;p. Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 166 Water Street, Woods Hole, MA 02543, USA;q. National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1315 East-West Highway, Silver Spring, MD 20910, USA;1. CSIRO Oceans and Atmosphere, Hobart, Tasmania, 7000, Australia;2. Centre for Marine Socioecology, University of Tasmania, Hobart, Tasmania, 7000, Australia;3. CSIRO Land and Water, Hobart, Tasmania, 7000, Australia;4. Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, 7001, Australia;5. RISE Research Institutes of Sweden, Agrifood and Bioscience, PO Box 5401, SE-402 29, Gothenburg, Sweden;6. Canadian Fisheries Research Network, Fisheries and Oceans Canada, St. Andrews Biological Station, St. Andrews, NB, E5B 2L9, Canada;1. Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E, Seattle, WA 98112, United States;2. Long Live the Kings, 1326 5th Ave. #450, Seattle, WA 98101, United States;3. Washington Department of Fish and Wildlife, 1111 Washington St. SE, Olympia, WA 98501, United States
Abstract:
Indicators have been recognised as a useful tool aiding the implementation of an ecosystem approach to fisheries in marine ecosystems. Studies, such as the IndiSeas project (www.indiseas.org), use a suite of indicators as a method of assessing the state and trends of several of the world's marine ecosystems. While it is well known that both fishing and climatic variability influence marine fisheries in the southern Benguela ecosystem there are currently few studies in support of fisheries management that make use of environmental indicators in order to include climatic impacts on marine fish populations. Trends in ecological, fishing and environmental indicators can be utilised in a way that allows an overall ecosystem trend to be determined, and can therefore be used to aid decision support within southern Benguela fisheries. In this study trends in indicators were determined using linear regressions across three time periods, Period 1: 1978–1993, Period 2: 1994–2003 and Period 3: 2004–2010. These time periods were selected based on the timing of regime shifts within the southern Benguela, including changes in upwelling, wind stress and temperature. Each ecological indicator received a score based on the direction and significance of the observed trend with respect to fishing. To account for the impacts of fishing and environmental drivers on ecological indicators, scores were adjusted by predetermined factors, depending on the extent and direction of trends in these indicators. Weightings were applied to correlated ecological indicators to account for their redundancy, and lessen their impact on overall ecosystem score. Mean weighted scores were then used to establish an overall ecosystem score for each time period. Ecosystem classification was determined as follows: 1–1.49 = improving, 1.5–2.49 = possibly improving, 2.5–3.49 = no improvement or deterioration, 3.5–4.49 = possible deterioration, 4.5–5 = deteriorating. The ecosystem was observed to neither deteriorate nor improve across Period 1 or 2 (mean weighted scores: 2.75 and 2.56 respectively), however, during Period 3 a possible improvement was observed (mean weighted score: 1.99). This study shows that the sequential analysis of suites of ecological, fishing and environmental indicators can be used in order to determine ecosystem trends, accounting for both the impacts of fishing and the environment on ecosystem components.
