| 1. |
|
|
| 2. |
- Cardinale, Massimiliano
(författare)
-
Rebuilding Mediterranean fisheries: a new paradigm for ecological sustainability
- 2013
-
Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 14, s. 89-109
-
Tidskriftsartikel (refereegranskat)abstract
- In Mediterranean European countries, 85% of the assessed stocks are currently overfished compared to a maximum sustainable yield reference value (MSY) while populations of many commercial species are characterized by truncated size- and age-structures. Rebuilding the size- and age-structure of exploited populations is a management objective that combines single species targets such as MSY with specific goals of the ecosystem approach to fisheries management (EAF), preserving community size-structure and the ecological role of different species. Here, we show that under the current fishing regime, stock productivity and fleet profitability are generally impaired by a combination of high fishing mortality and inadequate selectivity patterns. For most of the stocks analysed, a simple reduction in the current fishing mortality (Fcur) towards an MSY reference value (FMSY), without any change in the fishing selectivity, will allow neither stock biomass nor fisheries yield and revenue to be maximized. On the contrary, management targets can be achieved only through a radical change in fisheries selectivity. Shifting the size of first capture towards the size at which fish cohorts achieve their maximum biomass, the so-called optimal length, would produce on average between two and three times higher economic yields and much higher biomass at sea for the exploited stocks. Moreover, it would contribute to restore marine ecosystem structure and resilience to enhance ecosystem services such as reservoirs of biodiversity and functioning food webs.
|
|
| 3. |
- Friedman, Kim, et al.
(författare)
-
Management of sea cucumber stocks : patterns of vulnerability and recovery of sea cucumber stocks impacted by fishing
- 2011
-
Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 12:1, s. 75-93
-
Tidskriftsartikel (refereegranskat)abstract
- Identifying rates of change in the abundance of sea cucumbers under differing management regimes is fundamental to estimating commercial yields, identifying ecological interactions and facilitating management. Here, we review the status of sea cucumber stocks from a range of Pacific Island countries (Samoa, Tonga, Palau, Fiji and Papua New Guinea), some of which have had a moratorium on exports for up to a decade. We use a time-series approach to look at variation in sea cucumber presence, coverage and density from survey and re-survey data. Results give an appreciation of variation between 'high' status (less impacted) and depleted stocks. Survey data show marked declines in coverage and abundance as a result of artisanal fishing activity, and although species groups were not lost at a country level, local extirpation and range restriction was noted. Resilience and 'recovery' following cessation of fishing varied greatly, both among locations and among the species targeted. Worryingly, even after extended periods of moratorium, the density of some species was markedly low. In many cases, the densities were too low for commercial fishing, and may be at a level where the effective population size is constrained due to 'Allee' affects. From these results, we suggest that management regimes presently employed are generally not well aligned with the level of response to fishing mortality that can be expected from sea cucumber stocks. New adaptive, precautionary approaches to management are suggested, which would allow more timely interventions to be made, while refined information on stock dynamics is sought.
|
|
| 4. |
|
|
| 5. |
- Piccolo, John J, 1964-, et al.
(författare)
-
Conservation of endemic landlocked salmonids in regulated rivers : a case-study from Lake Vänern, Sweden
- 2012
-
Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 13:4, s. 418-433
-
Tidskriftsartikel (refereegranskat)abstract
- Conservation of migratory salmonids requires understanding their ecology at multiple scales, combined with assessing anthropogenic impacts. We present a case-study from over 100 years of data for the endemic landlocked Atlantic salmon (Salmo salar, Salmonidae) and brown trout (Salmo trutta, Salmonidae) in Lake Vänern, Sweden. We use this case-study to develop life history-based research and monitoring priorities for migratory salmonids. In Vänern, small wild populations of salmon and trout remain only in the heavily regulated Rivers Klar (Klarälven) and Gullspång (Gullspångsälven), and commercial and sport fisheries are maintained by hatchery stocking. These populations represent some of the last remaining large-bodied (up to 20 kg) landlocked salmon stocks worldwide. We found that one of four stocks of wild fish has increased since 1996; the other three remain critically low. Hatchery return rates for three of four stocks appear stable at roughly 1% and annual fisheries catch is roughly 75 metric tons, with an estimated 7.5% of hatchery smolts being recruited to the fishery; this also appears relatively stable since 1990. Our analysis reveals much uncertainty in key data requirements, including both river return and fisheries catch rates, estimates of wild smolt production and survival, and hatchery breeding and genetics protocols. These uncertainties, coupled with a lack of information on their riverine and lacustrine ecology, preclude effective management of these unique populations. We conclude with a framework for a life history-based approach to research and monitoring for Vänern salmon and trout, which should be applicable for all endemic, migratory salmonid populations.
|
|
| 6. |
- Sjöstedt, Martin, 1977
(författare)
-
Horizontal and vertical resource dilemmas in natural resource management: the case of African fisheries
- 2013
-
Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 14:4, s. 616-624
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract The world’s fisheries are under severe pressure. Yet, according to the marine trophic index, the health and stability of marine ecosystems vary greatly across countries. The argument developed and tested in this article holds that some of the sources of this variation can potentially be derived from differences in the character of two fundamental relationships in society – a horizontal one between resource users and a vertical relationship between the government and the resource users. The empirical analysis focuses on sub-Saharan Africa and finds that levels of ethnic and linguistic heterogeneity and levels of democracy in the year that each country declared its exclusive economic zone have a close relationship with ensuing marine exploitation patterns.
|
|
| 7. |
- Laugen, Ane
(författare)
-
Evolutionary impact assessment: accounting for evolutionary consequences of fishing in an ecosystem approach to fisheries management
- 2014
-
Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 15, s. 65-96
-
Tidskriftsartikel (refereegranskat)abstract
- Managing fisheries resources to maintain healthy ecosystems is one of the main goals of the ecosystem approach to fisheries (EAF). While a number of international treaties call for the implementation of EAF, there are still gaps in the underlying methodology. One aspect that has received substantial scientific attention recently is fisheries-induced evolution (FIE). Increasing evidence indicates that intensive fishing has the potential to exert strong directional selection on life-history traits, behaviour, physiology, and morphology of exploited fish. Of particular concern is that reversing evolutionary responses to fishing can be much more difficult than reversing demographic or phenotypically plastic responses. Furthermore, like climate change, multiple agents cause FIE, with effects accumulating over time. Consequently, FIE may alter the utility derived from fish stocks, which in turn can modify the monetary value living aquatic resources provide to society. Quantifying and predicting the evolutionary effects of fishing is therefore important for both ecological and economic reasons. An important reason this is not happening is the lack of an appropriate assessment framework. We therefore describe the evolutionary impact assessment (EvoIA) as a structured approach for assessing the evolutionary consequences of fishing and evaluating the predicted evolutionary outcomes of alternative management options. EvoIA can contribute to EAF by clarifying how evolution may alter stock properties and ecological relations, support the precautionary approach to fisheries management by addressing a previously overlooked source of uncertainty and risk, and thus contribute to sustainable fisheries.
|
|
| 8. |
- Pauly, Daniel, et al.
(författare)
-
China's distant-water fisheries in the 21st century
- 2014
-
Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 15:3, s. 474-488
-
Tidskriftsartikel (refereegranskat)abstract
- We conservatively estimate the distant-water fleet catch of the People's Republic of China for 2000-2011, using a newly assembled database of reported occurrence of Chinese fishing vessels in various parts of the world and information on the annual catch by vessel type. Given the unreliability of official statistics, uncertainty of results was estimated through a regionally stratified Monte Carlo approach, which documents the presence and number of Chinese vessels in Exclusive Economic Zones and then multiplies these by the expected annual catch per vessel. We find that China, which over-reports its domestic catch, substantially under-reports the catch of its distant-water fleets. This catch, estimated at 4.6 million t year(-1) (95% central distribution, 3.4-6.1 million t year(-1)) from 2000 to 2011 (compared with an average of 368 000 t year(-1) reported by China to FAO), corresponds to an ex-vessel landed value of 8.93 billion year(-1) (95% central distribution, 6.3-12.3 billion). Chinese distant-water fleets extract the largest catch in African waters (3.1 million t year(-1), 95% central distribution, 2.0-4.4 million t), followed by Asia (1.0 million t year(-1), 0.56-1.5 million t), Oceania (198 000 t year(-1), 144 000-262 000 t), Central and South America (182 000 t year-1, 94 000299 000 t) and Antarctica (48 000 t year(-1), 8 000-129 000 t). The uncertainty of these estimates is relatively high, but several sources of inaccuracy could not be fully resolved given the constraints inherent in the underlying data and method, which also prevented us from distinguishing between legal and illegal catch.
|
|
| 9. |
|
|
