Annual Progress Report N°7

Abstract

COPAS Sur-Austral has five Research Lines and one Outreach & Transfer line, as follows: R+D Line 1: Oceanographic observation for the sustainable development of aquaculture (PI: G. Daneri); R+D Line 2: Environmental variability and ecosystem patterns associated with changing freshwater inputs in Patagonian fjords (PI: F. Tapia); R+D Line 3: Ecosystem Variability and Demersal and Pelagic Fisheries (PI: L. Castro); R+D Line 4: An ecosystem approach to Patagonian Fisheries (PI: S. Neira); R+D Line 5: Marine Biosafety and Biotechnology (PI: R. González); and R+D Line 6: Technological and Knowledge Transfer (PI: R. Norambuena), which is responsible for transferring oceanographic information and knowledge, and links COPAS Sur-Austral with the productive sector and public services. Dr. Silvio Pantoja is the Director of the Center. Research: All research lines converge in addressing the three overarching themes set forth in the Continuity Plan: i) sustainable aquaculture research, including studies on toxic plankton and pathogens (R+D lines 1, 5 and 2); ii) regional management of pelagic, demersal and benthic fisheries (R+D lines 3 and 4); and iii) the effects of freshwater inputs at the ecosystem level (R+D lines 1, 2 and 3), including sediment studies (R+D Line 2). Data from continuous oceanographic observation platforms with state-of-the-art technology is important to all Research Lines. Thus, we continued with our observational platforms in: Reloncaví (LOBO buoy); Jacaf/Puyuhuapi (HOBO-U30 Muelle Isla Magdalena, HOBO-U30 Jacaf 1 2, and the oceanographic and meteorological buoy YSI 6600-V4); Martinez and Baker channels array of conductivity, temperature, and pressure sensors; Caleta Tortel time series of temperature and sea level; and glider observations in the Corcovado Gulf and in the Magellan Strait. Our “investment” in infrastructure at Caleta Tortel (vessel L/C Sur-Austral, enlarged laboratory with storage space, and a pick-up truck) has eased our way of doing science in this remote area as well as increased our ties to the local community through outreach activities and a closer interaction with the local elementary school. The sustainable development of aquaculture needs knowledge on the structure and basic functioning of ecosystems, including circulation, ventilation, inputs of freshwater, natural variability of oxygen, inorganic nutrients, dissolved organic matter dynamics, and natural variability of the capability of water column microbes to degrade organic molecules. Gaps persist in the knowledge of key health management at the scale of farms, as well as epidemiological aspects at the scale of fjord basin. Also, oceanographic modelling tools need to be incorporated to current productive practices within the salmon farming industry. We concentrated efforts in the Puyuhuapi-Jacaf area, an ecosystem that is intensely used for aquaculture activities (salmon farms). During Year 7, a multidisciplinary (and multi-national) field experiment was undertaken with the goals of studying: a) the environmental changes that trigger the occurrence of the annual late winter-spring phytoplankton bloom; b) the coupling between primary and bacterial secondary production; c) carbon fluxes in the water column; d) organic matter degradation rates; e) benthic communities and their role in the organic matter cycling; and f) aquaculture-derived contaminants. The results will allow to generate and test meaningful environmental carrying capacity models that should substantially contribute to the fjord environmental protection by providing elements of sustainability for the salmon industry. We advanced in understanding toxic plankton and pathogens that may seriously affect aquaculture activity (e.g., genetic variability of Alexandrium catenella, haplotypes of Caligus rogercresseyi), the effects of marine toxins on filtering bivalves (e.g., saxitoxin on Mytilus, mechanisms of Heterosigma akashiwo toxicity), and bioactive compounds for use in aquaculture (e.g., dietary supplement with antioxidant and anti-inflammatory properties). In terms of developing modelling tools, we moved forward with the salmon farming company Salmones Cupquelán S.A., and are currently calculating different risk scenarios under the fuzzy logic model approach. Regional management of pelagic and demersal fisheries needs to be based on knowledge of food webs that support the main fisheries in the southern region, impact of environmental variability on connectivity and phenology of fishery resources, and a more holistic ecosystem approach aimed at stock recovery. Combining ecosystem and single-species models to project the biomass of Sprattus fuegensis (an important consumer of COPAS PFB-31 11 zooplankton and a significant prey in the diet of demersal fish stocks) under different fishing scenarios, led us to conclude that the current biological reference point (Maximum Sustainable Yield, MSY) may be too aggressive for this species, risking the sustainability of this stock as well as those of predator fish. New results about spawning areas of the small pelagic resources in Northern Patagonia (Sprattus fuegensis, Strangomera bentincki and Engraulis ringens) demonstrate that, although these fishes may usually be located in the same regions as adults, they segregate spatially for spawning and nursing. Thus, environmental changes (either natural or anthropogenic) may affect the dynamics of these populations in a different manner given their separate distribution at life stages when they are more susceptible to natural mortality. These findings are important for decision-making processes related to establishing areas of shelter in order to improve the status of the fisheries resources. According to the National Fisheries and Aquaculture Law, there is an urgent need for recovery plans of demersal fisheries whose stocks in southern Chile are either overexploited (southern hake and hoki) or depleted (kingkilp and skates), and so far strategies are evaluated using only the single-species approaches. Our multi-species and ecosystem approaches indicate that the biomass of southern hake and hoki are far from the biomass that produces the MSY, and that applying fishing mortality FMSY does not allow recovery to biomass levels at MSY. Therefore, disregarding trophic interactions among fish stocks may delay and even preclude recovery of these demersal resources. During Year 7, COPAS Sur-Austral researchers continued as members of scientific and technical committees that have the responsibility of assigning the range for the Biologically Acceptable Catch, which is the base for the Total Allowable Quota.