SPACC Theme 1: Long-term changes in ecosystems - retrospective analysis
Theme representatives: J. Alheit, T. Baumgartner
The focus of Theme 1 is to explore how fish populations respond to ocean climate over time spans of hundreds to thousands of years. Long time series of data and modelling are used to determine how variation in the coupled ocean-atmosphere climate system affects the ecosystems in which small pelagic fish are important. It has a global and atmospheric perspective because climatic teleconnections are believed to be involved. The paleoecological component is driven by the fundamental discovery that anoxic sediments in regions with small, pelagic fish contain scales that can be used to reconstruct time series of abundance of those fish over thousands of years.
Three meetings related to Theme 1 were held over the last two years. “Major Turning Points in the Structure and Functioning of the Benguela Ecosystem” was the topic addressed by a GLOBEC-SPACC/IDYLE/BENEFIT meeting (Cape Town, South Africa, 12-16 February 2001). This meeting was the first of a series of similar workshops that will investigate turning points in other regions of the world that support large populations of sardine and anchovy. The Cape Town meeting was followed by a GLOBEC-SPACC/IAI workshop on “Comparative Studies of Long-Term Variability of Small Pelagic Fishes in the Humboldt and California Current Ecosystems” (Lima, Peru, 29 May-1 June 2001). Finally, a SPACC/GLOBEC Workshop on Paleoceanography (Munich, Germany, 10-13 October 2001) brought together research teams carrying out high resolution analyses of sediment cores from different anoxic sites in order to compare and cross-calibrate methodologies and co-ordinate future co-operation and comparisons. Overviews of the outputs of those three meetings were published in the April 2001 and April 2002 issues of the GLOBEC Newsletter.
A workshop, “SPACC in the Kuroshio System”, was held 9-10 December 2003 at the Ocean Research Institute, University of Tokyo, Japan). This workshop included presentations of time series concerning anchovy, sardine, and herring in the North Pacific, as well as other regions, and possible mechanisms for the observed fluctuations.
SPACC Theme 2: Comparative population dynamics
(including WG3 - Resource productivity and WG9 - Resource availability)
Theme representatives: J. Hunter (ex-officio)
Fish biomass per unit of stock is used to compute and compare quantitative estimates of small pelagic fish production and, most important, production of biomass or recruits per unit area of spawning and feeding habitats. This work provides a quantitative basis for comparing fish production between and within all systems in standard production units.
A review paper (Jacobson et al., 2001) emanated from the outcome of a workshop in Dartmouth, Canada. This paper is on surplus production and climate change in the great sardine and anchovy fisheries. Recent activities related to Theme 2 include an IOC/SPACC Study Group on “Use of Environmental information on the management of pelagic fish populations” (see GLOBEC Newsletter, April 2002). The group met for the first time in Cape Town (3-5 September 2001). Its second and final meeting was at IOC/UNESCO in Paris, November 2002 and resulted in GLOBEC Special Contribution No. 6.
SPACC Theme 3: Reproductive habitat dynamics
(including WG7 - Spawning and nursery habitat quality dynamics, WG8 - Spawning habitat dimensions and location and WG6 - Daily growth and zooplankton)
Theme representatives: D. Checkley and C. Roy
The focus of Theme 3 is comparisons between systems to identify how small pelagic fishes adapt their reproductive strategies to the various kinds of physical forcing and mesoscale features of their habitat, and how such systems constrain fish productivity. A central hypothesis is that changes in productivity are caused by changes in the temporal and spatial dimensions of the spawning habitat, as well as its location and quality. A major component of Theme 3 is based on the use of CUFES for mapping egg distributions and to achieve a quantitative description of the spatio-temporal dynamics of spawning. The use of hydrodynamic models coupled with NPZD and IBM models is also a central focus, in order to investigate the links between environment variability, spawning, and recruitment success. Ecosystems are compared to separate physical forcing from stock-dependent effects on spawning and recruitment selection and to examine the extent to which productivity is limited by space and time variation in spawning habitat.
Activities related to Theme 3 have a wide geographical range and cover the Humboldt, Benguela, and California Current Systems and the Bay of Biscay. A SPACC/IDYLE/ENVIFISH workshop held in Cape Town (September 2001) focused on spatial approaches of the dynamics of coastal pelagic resources and their environment in upwelling areas (see GLOBEC Newsletter, April 2002). The meeting aimed at synthesizing the state of the art concerning recent theoretical achievements, analysis techniques and modeling tools used for the integration of spatial structures in the study of the dynamics of marine populations and their environments. The outcome was published in GLOBEC Report 16 (Van der Lingen et al., 2002). On-going CUFES sampling is currently taking place in California (16 cruises 1996-2002), Mexico (10 cruises 2000-2002), Peru (5 crusies 1999-2001) and Chile (4 cruises 1999-2001), thanks to IAI funding. CUFES is also used by South Africa (Benguela), Spain and France (Bay of Biscay), and Canada (East Coast). The automation of detection and counting of fish eggs in CUFES in real-time by use of machine vision is nearing completion.
A workshop and meeting on characterizing and comparing the spawning habitats of small, pelagic fish was held in Concepcion, Chile 12-16 January 2004. The meeting also addressed the use of daily egg production method to assess the spawning biomass of small, pelagic fish.
SPACC Theme 4: Economic implications of climate change
(including WG10 - Economic consequences and links to IGBP Food and Fibre and IHDP)
Theme representative: J. Hunter (ex-officio)
A workshop on the economics of small pelagics and climate change will take place in Portsmouth, UK, in September 2004. Some of the issues to be discussed at this workshop would be (a) effects of low- and high-frequency climatic events on fish productivity; (b) impacts of climate change on harvesting and processing capacity and fisheries investments; (c) economic benefits of cooperative management of transboundary stocks; (d) impacts of the international trade of small pelagic fish and their substitutes; and (e) the value of improved long-range climate prediction.