WGAQUA, a focal point for much of the organization’s work conducted in the field of aquaculture (fish, shellfish and aquatic plant farming), met this year in Rhode Island in what was the conclusion of its first three-year term following its establishment in 2013 from a merger of two previous groups.
The group’s experts are tasked with synthesizing the aquaculture activities of ICES expert groups, identifying emerging topics, and responding to advisory request from clients. In addition, WGAQUA haskept track of and reviewed the state of knowledge in terms of three key scientific theme areas: the impact of aquaculture on benthic (bottom) habitats, pest management, and ecosystem interactions. These issues have become increasingly prominent over the past two decades, with aquaculture science having changed courses to take the environmental effects of fish and shellfish farming into greater considerationin order to ensure sustainable production.
The first issue involves the release of organic effluents from intensive finfish farming in the form of waste feed and faeces to the surrounding marine environment, especially the seafloor areas over which open-net pens are set. Aquaculture of bivalves also produced large quantities of faeces. These materials settle quickly on the bottom where they may greatly increase organic loading within and immediately around farm sites, a process which can lead to oxygen depletion. For traditional cultivation locations, the development of tools for detecting benthic impacts from aquaculture has been of considerable interest; however, so far much of the research has centred on muddy sea bottom habitats. WGAQUA’s scientists have been working to recognize and assess ways of analyzing what effects the rearing of fishin this way can have on coarse and mixed substrata bottoms as well as eelgrass and maerl beds.
The management of pest species in finfish mariculture has received increased attention in the recent past, particularly in reference to sea lice management in salmon farms. The development of treatment regimes has mainly focused on the efficiency of control methods and therapeutants. The active ingredients in therapeutants may enter the aquatic environment through a variety of pathways (e.g. dissolution, particle transport and sedimentation) and thus may reside in the water column or in benthic ecosystems and expose non-target organisms. To date, little work has addressed these issues at an ecosystem level. Moreover, decisions relating to pest management by the use of therapeutants are commonly made without adequate regard to other possibile management options. WGAQUA members are analysing the environmental effects of sea lice pest management with the goal of supporting decisions relating to various treatment options.
An increasing number of studies have shown that the presence of an aquaculture farm may affect wild fish and other species in a given area. Fish farms may attract wild fish because of the presence of feed and other waste products, altered benthic communities associated with farms, and the physical structure of farms, which may offer alternate refuges or food sources. In contrast, anecdotal evidence suggests that some fish have altered their spawning and migratory behaviour to avoid aquaculture areas. With respect to the attraction of fish to farms, their consumption of waste products may alter the quality of the fish (size, condition, texture, flavour, etc.). WGAQUA members are analysing issues relating to the attraction and repulsion of wild populations by fish and shellfish farms with the goal of assessing the impact on wild populations, individuals and life-stages.
Expectations are high that aquaculture production will help fill the growing gap between the supply and demand for fishery resources. However, this need for aquaculture development comes with an increasing demand for science to help minimize adverse environmental interactions and decrease the reliance on wild fishery resources for feed ingredients. In addition, environmental factors limiting the production of cultured seafood, including climate change, need to be understood so that mitigation measures and new technologies can be developed.
The ICES Science Plan recognized the increasing demand for aquaculture science and advice, and WGAQUA was strategically placed in a position to help fulfill these needs by tackling many of the major issues that challenge aquaculture development. The future role of ICES in providing aquaculture advice will be discussed at a dialogue meeting on 1-2 June in Bergen, Norway. This dialogue is organized with input from WGAQUA to bring together policy-makers, managers, industry, and scientists, to identify the scientific and advisory needs in the field.
WGAQUA’s official 2015 report is expected to be published at the end of April.
Aquaculture pens; photo - Stefanos Kyriazis, Fotolia