Effects of fishing and acidification‐related benthic mortality on the southeast Australian marine ecosystem

Oceanic uptake of anthropogenic carbon dioxide (CO₂) is altering the carbonate chemistry of seawater, with potentially negative consequences for many calcifying marine organisms. At the same time, increasing fisheries exploitation is impacting on marine ecosystems. Here, using increased benthic‐invertebrate mortality as a proxy for effects of ocean acidification, the potential impact of the two stressors of fishing and acidification on the southeast Australian marine ecosystem to year 2050 was explored. The individual and interaction effects of the two stressors on biomass and diversity were examined for the entire ecosystem and for regional assemblages. For 61 functional groups or species, the cumulative effects of moderate ocean acidification and fishing were additive (30%), synergistic (33%), and antagonistic (37%). Strong ocean acidification resulted in additive (22%), synergistic (40%), and antagonistic (38%) effects. The greatest impact was on the demersal food web, with fishing impacting predation and acidification affecting benthic production. Areas that have been subject to intensive fishing were the most susceptible to acidification effect, although fishing also mitigated some of the decline in biodiversity observed with moderate acidification. The model suggested that ocean acidification and long‐term fisheries exploitation could act synergistically with the increasing sensitivity to change from long‐term (decades) fisheries exploitation potentially causing unexpected restructuring of the pelagic and demersal food webs. Major regime shifts occur around year 2040. Greater focus is needed on how differential fisheries exploitation of marine resources may exacerbate or accelerate effects of environmental changes such as ocean acidification.     

Food security and marine capture fisheries: characteristics, trends, drivers and future perspectives

World population is expected to grow from the present 6.8 billion people to about 9 billion by 2050. The growing need for nutritious and healthy food will increase the demand for fisheries products from marine sources, whose productivity is already highly stressed by excessive fishing pressure, growing organic pollution, toxic contamination, coastal degradation and climate change. Looking towards 2050, the question is how fisheries governance, and the national and international policy and legal frameworks within which it is nested, will ensure a sustainable harvest, maintain biodiversity and ecosystem functions, and adapt to climate change. This paper looks at global fisheries production, the state of resources, contribution to food security and governance. It describes the main changes affecting the sector, including geographical expansion, fishing capacity-building, natural variability, environmental degradation and climate change. It identifies drivers and future challenges, while suggesting how new science, policies and interventions could best address those challenges.     

Reconstruction of coral reef fisheries catches in American Samoa, 1950–2002

Fisheries catches from Pacific Island coral reefs are rarely recorded in official statistics. Reconstruction of catch estimates with limited hard data requires interpolation and assumptions, justifiable only by the unsatisfactory alternative of continued substitution of zero catches, a common policy interpretation for ‘no data’. Uncertainties associated with reconstructions are high, requiring conservative estimation. American Samoan domestic fisheries consist of an artisanal, small-boat sector, whose commercial catches are reported, and a shore-based subsistence sector, with no regular reporting. Our catch reconstruction (with large pelagic species removed) suggested a 79% decrease in catches between 1950 (752 t) and 2002 (155 t). Accounting for rapid human population growth on the main island, the per capita catch rate may have declined from 36.3 kg·person⁻¹ year⁻¹ in 1950 to 1.3 kg·person⁻¹ year⁻¹ by 2002, while the catch rate for the inhabited outer islands has been independently reported as 58.6 kg·person⁻¹ year⁻¹. Catch per area of coral reef (to 50-m depth) may have declined from 5.5 to 0.7 t km⁻² year⁻¹ for the main island, and from 9.1 to 4.9 t km⁻² year⁻¹ for the outer islands, for 1950 and 2002, respectively. Summed for 1950–2002, our reconstruction suggested a 17-fold difference between reconstructed estimates and reported statistics.     

The cost to government of maintaining a commercially unviable fishery: The case of newfoundland 1981/82 to 1990/91

The commercial fishery for northern cod off Newfoundland has been closed since 1992. Since then, the recreational “food fishery”; has also been closed, as have the fisheries for many additional cod and other groundfish stocks. The Newfoundland fisheries had been commercially unviable for many years before the closures. This article records the federal and provincial governments’ financial outlays (expenditures, transfer payments to individuals, subsidies, net equity purchases, and net loans) on the fishery during the decade following 1981. Special emphasis is placed on the cost of the financial restructuring of the industry in the mid‐1980s, net unemployment insurance payments, and social overhead capital expenditures.