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Biomedical subjects

Michel J Kaiser

Publications and source records attributed to Michel J Kaiser.

6 recordsLinked to original sources
PubMed2006

On effects of trawling, benthos and sampling design.

The evidence for the wider effects of fishing on the marine ecosystem demands that we incorporate these considerations into our management of human activities. The consequences of the direct physical disturbance of the seabed caused by towed bottom-fishing gear have been studied extensively with over 100 manipulations reported in the peer-reviewed literature. The outcome of these studies varies according to the gear used and the habitat in which it was deployed. This variability in the response of different benthic systems concurs with established theoretical models of the response of community metrics to disturbance. Despite this powerful evidence, a recent FAO report wrongly concludes that the variability in the reported responses to fishing disturbance mean that no firm conclusion as to the effects of fishing disturbance can be made. This thesis is further supported (incorrectly) by the supposition that current benthic sampling methodologies are inadequate to demonstrate the effects of fishing disturbance on benthic systems. The present article addresses these two erroneous conclusions which may confuse non-experts and in particular policy-makers.

Animals↗
PubMed2006

The role of ecolabeling in fisheries management and conservation.

The Marine Stewardship Council (MSC) regulates the ecolabeling of products from fisheries with the aim of promoting sustainable fishery practices. To date 11 fisheries have attained full certification and a further 7 are under review. Together these fisheries offer 220 ecolabeled marine products to consumers. Despite great potential to encourage sustainable fisheries, and thereby bring conservation benefits to marine systems, a range of issues may limit the wider uptake of MSC ecolabeled products. These include a general lack of consumer concern for marine fishes and sustainable fisheries, an absence of guaranteed continued financial benefits to participating fishers, and difficulties of quality assurance that are related to complexities of monitoring compliance of marine fisheries. In addition, it is apparent that property rights over the fishery seem to be an essential prerequisite for engagement in MSC, and this is one major impediment to wider uptake of the scheme in current marine fisheries, which tend to be open access. Some modifications to the current scheme may be needed if wider participation of marine fishers is to be achieved. These may include a tiered approach to certification, certification of fishers rather than fisheries, governmental facilitation to assist the latter and greater engagement with retailers and buyers rather than individual consumers. None of these changes will occur without constructive engagement of government, retailers, and the fishing industry.

Conservation of Natural Resources↗
PubMed2006

Conservation benefits of temperate marine protected areas: variation among fish species.

Marine protected areas, and other fishery management systems that impart partial or total protection from fishing, are increasingly advocated as an essential management tool to ensure the sustainable use of marine resources. Beneficial effects for fish species are well documented for tropical and reef systems, but the effects of marine protected areas remain largely untested in temperate waters. We compared trends in sport-fishing catches of nine fish species in an area influenced by a large (500-km2) towed-fishing-gear restriction zone and in adjacent areas under conventional fishery management controls. Over the period 1973-2002 the mean reported weight of above-average-sized (trophy) fish of species with early age at maturity and limited home range was greatest within the area influenced by the fishing-gear restriction zone. The reported weight of trophy fish of species that mature early also declined less and more slowly over time within the area influenced by the fishing-gear restriction zone. Importantly, the mean reported weight of trophy fish of species that mature late and those that undertake extensive spatial movements declined at the same rate in all areas. Hence these species are likely to require protected areas > 500 km2 for effective protection. Our results also indicated that fish species with a localized distribution or high site fidelity may require additional protection from sport fishing to prevent declines in the number or size of fish within the local population.

Animals↗
PubMed2006

Sensitivity of marine-reserve design to the spatial resolution of socioeconomic data.

Socioeconomic considerations should have an important place in reserve design. Systematic reserve-selection tools allow simultaneous optimization for ecological objectives while minimizing costs but are seldom used to incorporate socioeconomic costs in the reserve-design process. The sensitivity of this process to biodiversity data resolution has been studied widely but the issue of socioeconomic data resolution has not previously been considered. We therefore designed marine reserves for biodiversity conservation with the constraint of minimizing commercial fishing revenue losses and investigated how economic data resolution affected the results. Incorporating coarse-resolution economic data from official statistics generated reserves that were only marginally less costly to the fishery than those designed with no attempt to minimize economic impacts. An intensive survey yielded fine-resolution data that, when incorporated in the design process, substantially reduced predicted fishery losses. Such an approach could help minimize fisher displacement because the least profitable grounds are selected for the reserve. Other work has shown that low-resolution biodiversity data can lead to underestimation of the conservation value of some sites, and a risk of overlooking the most valuable areas, and we have similarly shown that low-resolution economic data can cause underestimation of the profitability of some sites and a risk of inadvertently including these in the reserve. Detailed socioeconomic data are therefore an essential input for the design of cost-effective reserve networks.

Animals↗
PubMed2005

Density dependence, spatial scale and patterning in sessile biota.

Sessile biota can compete with or facilitate each other, and the interaction of facilitation and competition at different spatial scales is key to developing spatial patchiness and patterning. We examined density and scale dependence in a patterned, soft sediment mussel bed. We followed mussel growth and density at two spatial scales separated by four orders of magnitude. In summer, competition was important at both scales. In winter, there was net facilitation at the small scale with no evidence of density dependence at the large scale. The mechanism for facilitation is probably density dependent protection from wave dislodgement. Intraspecific interactions in soft sediment mussel beds thus vary both temporally and spatially. Our data support the idea that pattern formation in ecological systems arises from competition at large scales and facilitation at smaller scales, so far only shown in vegetation systems. The data, and a simple, heuristic model, also suggest that facilitative interactions in sessile biota are mediated by physical stress, and that interactions change in strength and sign along a spatial or temporal gradient of physical stress.

Analysis of Variance↗