Environmental effects on stocks

Environmental effects on stocks

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Many fish stocks vary naturally as a result of the effects of the environment, even in the absence of fishing. For example, recruitment of prawns can be affected by rainfall. Weather events, ocean currents, changes in climate and disease can all affect fish spawning, recruitment and growth, resulting in environmentally-driven changes in abundance. Where links have been established between environmental factors and stock abundance for a given species, these are outlined in the species chapters.

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The stock status classification provided for each stock does not take into account the effects of fishing on the marine ecosystem or environment. As discussed previously, these elements of the broader concept of ecologically sustainable development tend to be considered at the fishery level, rather than the stock level. It is envisaged that future companion reports will provide broader assessments of Australian fisheries that will include formal classification of fisheries based on the effects of fishing on the marine environment. Although no formal classification has been given, the effects of fishing on the marine environment are briefly explored in each chapter, and measures that have been put in place to mitigate detrimental effects are described.

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Non-fishing factors that affect the sustainability of fish stocks

Along with fishing pressure and natural environmental factors, human activities that are unrelated to fishing can have a substantial impact on the sustainability of fish stocks—for example, oil and gas exploration, the clearing of mangroves for coastal development or sediment loads in river discharges. Although the impacts of human activities are not discussed on a species-by-species basis in the Status of Australian fish stocks reports 2016, these factors may, in some cases, have a greater impact on fish stocks than fishing.