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1.
Social-ecological complexity challenges conservation-oriented interventions even in settings with a small number of actors and conflicts involved. This article examines the development and trajectory of King and Snow Crab fisheries in the Cape Horn Biosphere Reserve (BR), the highly remote but globally connected Southern tip of the Americas. The feasibility of the Chilean legal instrument of Marine Management Areas (MMA) is assessed as a tool for mitigating impacts of overfishing in the area. Examining the local fishers’ perspectives in complement to a context analysis we find that external management models such as the MMA are not suited to make Cape Horn fisheries sustainable. Instead, efforts should be dedicated to a continuous process of stakeholder collaboration for developing site-specific management concepts and structures. These should be embedded in the larger BR initiative. Considering the area's particular conditions, several recommendations for such a process are formulated. 相似文献
2.
Sandy beaches face increasing anthropogenic pressures, with vehicle traffic being ecologically highly harmful. Ghost crabs (Fam. Ocypodidae) are conspicuous on many beaches, and they have been used as a bio‐monitoring tool to measure the ecological responses to human disturbance. However, the mechanisms causing declines in crab numbers are unknown, yet conservation must target the actual impact mechanisms. Therefore, we quantified the magnitude and mechanisms of off‐road vehicle (ORV) impacts on ghost crabs, addressing three key questions: (i) Does abundance of ghost crabs respond to traffic intensity?; (ii) Can burrows protect crabs from vehicles? and (iii) Can mortalities caused by vehicles contribute to population declines? ORV‐impacts were measured on North Stradbroke Island (Australia) for Ocypode cordimanus and Ocypode ceratophthalma. Crab densities were significantly lower in areas subjected to heavy beach traffic, suggesting direct crushing by vehicles. Burrows only partially protect crabs against cars: all individuals buried shallow (5 cm) are killed by 10 vehicle passes. Mortality declines with depth of burrows, but remains considerable (10–30% killed) at 20 cm and only those crabs buried at least 30 cm are not killed by ORVs: these ‘deep‐living’ crabs represent about half of the population. After crabs emerge at dusk they are killed in large numbers on the beach surface. A single vehicle can crush up to 0.75% of the intertidal population. While conservation measures should primarily regulate night traffic, our results also emphasise that the fossorial life habits of sandy beach animals cannot off‐set the impacts caused by ORVs. 相似文献
3.
A method is presented to define principal areas for fisheries at high spatial resolution applicable to be implemented into marine spatial planning procedures. Vessel monitoring system (VMS) data from 2005 to 2006 are acquired to determine vessel-based fishing effort. Principal areas for the German exclusive economic zone (EEZ) are defined as areas in which 75% of the effort of either year is carried out. Examples are given for the 5 most abundant fisheries in the German EEZ in terms of vessel-based effort, i.e. gill netting, pelagic trawling, demersal otter board trawling and beam trawling >300 and <300 HP. A historical comparison for demersal otter board trawling shows relative stability of spatial utilization patterns in the North Sea section of the EEZ. 相似文献
4.
Graham D. Sherwood Rick M. Rideout Susan B. Fudge George A. Rose 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2794
Cod populations in Newfoundland and Labrador waters have shown differing growth, condition and recruitment since near-universal declines in these properties during the cold period of the late 1980s and early 1990s. To assess the influence of variable prey communities on these parameters, we compared cod energetics and diet in populations off Labrador and the northeast and south coasts of Newfoundland. Many properties were highest in the southern group(s) and lowest in the northern group(s), including growth, somatic condition, liver index and age-at-maturity. Most differences could be explained by variations in diet, as measured by stomach contents and stable carbon isotopes (δ13C). The diet of Labrador cod consisted almost entirely of northern shrimp (Pandalus borealis), and these cod displayed the most benthic δ13C signatures. Northeast cod had a more varied diet that included capelin and other fish, but still had mostly benthic δ13C signatures, suggesting the importance of benthic prey like shrimp in this population. South coast cod exhibited the most varied diet, including capelin (Mallotus villosus), zooplankton, crabs and other fish, and had the most pelagic δ13C signatures. Among and within populations, the benefits of a more pelagic diet in medium-sized (30–69 cm) cod included higher somatic condition, higher liver index (lipid stores) and greater spawning potential (decreased incidence of atresia). It is hypothesized that major rebuilding of Newfoundland and Labrador cod stocks will require a return to a system that supports mostly pelagic feeding (i.e. capelin) in cod. 相似文献
5.
New Zealand seamounts support major fisheries for several deepwater fish species, including orange roughy (Hoplostethus atlanticus) and smooth oreo (Pseudocyttus maculatus). Although a high proportion of features in the depth range 500–1000 m have been fished, very little is known about the ecological impacts of bottom trawling on seamounts. The potential impact is likely to be influenced by the spatial extent and frequency of fishing. A new index is presented to assess the relative intensity of trawling on New Zealand seamounts. The fishing effects index (FEI) incorporates information on the density of fishing on the seamount as a proportion of the seabed area and also on tow direction. Detailed fisheries data from more than 250 000 tows were examined to calculate FEI for New Zealand seamounts. The most intensively fished seamounts were on the south Chatham Rise, an area characterised by a large number of relatively small features which were fished serially for orange roughy in the 1980s and 1990s. Other seamounts with high FEI were on the north Chatham Rise, Challenger Plateau, and off the east coast of the North Island. A range of sensitivity analyses indicated that the general rankings of seamounts were relatively robust to the choice of arbitrary thresholds used to assign tows to seamounts. 相似文献
6.
《Journal of Sea Research》2007,57(2-3):187-197
To protect the main nursery area of plaice, an area called the ‘Plaice Box’ was closed to trawl fisheries with large vessels in 1989, with the expectation that recruitment, yield and spawning stock biomass would increase. However, since then the plaice population has declined and the rate of discarding outside the Plaice Box has increased, suggesting an offshore shift in spatial distribution of juvenile plaice. Using research vessel survey data collected since 1970, the change in distribution of juvenile age groups was analysed in relation to the distance to the coast. Further, a comparison of the distribution of different length classes of plaice between three historic periods was made (1902–1909; 1983–1987; 1999–2003). A shift towards deeper water of larger-sized plaice (20–39 cm) is apparent already before the 1980s and may be related to the decrease in the number of competitors or predators. An offshore shift in the distribution of young plaice occurred in the 1990s most likely in response to higher water temperatures that may have exceeded the maximum tolerance range or increased the food requirements above the available food resources. A decrease in competition with larger plaice offshore, possibly in combination with increased inshore predation by cormorants and seals, may also have played a role. The offshore shift in distribution has reduced the effectiveness of the Plaice Box as a technical measure to protect the under-sized plaice from discarding, since an increased proportion of the population of undersized plaice is moving to the more heavily exploited offshore areas. 相似文献
7.
This study aims to investigate and model driving forces that lead to increased fishing pressure and an altered state of the environment in the coastal areas near Samsun on the Turkish Black Sea coast. We have applied a modified DPSIR model to structure our investigation and analysis and have investigated the drivers that generate fishing pressure in the Samsun fisheries. The overall health of the ecosystem is declining, and there is a consistent trend of deterioration in the condition of the three major species targeted by the trawl fisheries. Although introduced invasive species have brought significant changes to the Black Sea, it is clear that the state of the environment is significantly and negatively affected by the pressure exerted by fisheries. Fishing pressure has to a certain extent been redirected to pelagic trawling as bottom trawling has become less profitable and a rise in catch capacity has levelled off. This reduction is, however, offset by an increase in illegal trawling and dredging by a very rapidly growing sector of multi-purpose small boats, resulting in a considerable increase in the overall accumulated engine power of fishing boats in Samsun during 2000–2005. Fisheries in Samsun, in particular sea snail fisheries, have constituted a frontier of sorts open to the poorer populations of Samsun during the last 20 years, and, thereby, constitute one of the major drivers for fishing pressure. We identify eight drivers of importance for the period 2000–2005. Although the authorities can impact all or most of those drivers, most of them are beyond the scope of conventional ‘fisheries management’. 相似文献
8.
《Marine Policy》2016
The harbour porpoise (Phocoena phocoena) is the focus of a range of conservation efforts and policies, including the Habitats Directive, aimed at reducing the bycatch of non-target species in gillnet fisheries. This paper describes the governance process and analyses the governance mechanisms and conflicts surrounding ongoing fisheries management planning with a focus on two Natura 2000 sites in the Danish part of the Skagerrak Sea designated to protect harbour porpoises. Responsibility for developing fisheries management for Natura 2000 sites is solely the remit of the fisheries agency, including mechanisms related to stakeholder involvement. This approach fuels the efficiency of the decision making process, while full transparency and/or co-decision becomes less of a given within a ministry for an economic sector compared with the environment ministry. In relation to porpoises, conflicts are driven mainly by the economy and the varying perceptions of the bycatch issue, with great differences between government, NGO's and fishers. Interviews with fishers and fishing effort data reveal intra-sectoral conflicts pertaining to the incompatibility of active trawling and passive gillnetting in the areas. The paper questions the overall approach to managing the harbour porpoise bycatch issue in light of Natura 2000 and discusses the role of science and its high level of influence in this planning process. 相似文献
9.
New Zealand has a large exclusive economic zone (EEZ) that contains a variety of marine habitats and commercially-important species. The commercial fishing industry operating within New Zealand's EEZ is of significant value to the economy and fisheries resources are managed through the extensive use of Individual Transferable Quotas (ITQs). One of the benefits of ITQs has been to better align some of the private incentives of quota owners with the public interest. These incentives contributed to an initiative proposed by the fishing industry to close large areas of New Zealand's EEZ to protect the seabed from trawling. These closed areas are termed benthic protection areas (BPAs) and protect the benthic biodiversity of about 1.1 million square kilometres of seabed—approximately 30% of New Zealand's EEZ. A significant proportion of New Zealand's known seamounts and active hydrothermal vents are protected by these closed areas. We describe and discuss the criteria used to select BPAs and some of the criticism of this marine protection initiative. We argue that the assignment of strong property rights in fishing resources was an important precondition to an industry initiative that has a significant public benefit. Where private and public interests are well aligned, government can adopt an enabling and facilitation role, ceding direct control of processes in order to get the results the align with the public interest. 相似文献
10.
Commercial fisheries are heavily dependent upon the combustion of fossil fuels and as such contribute to increased atmospheric concentrations of greenhouse gases and the concomitant impact on the world's climate. The fuel use and greenhouse gas intensity of a fishery is a function of several variables. One that has not been previously investigated is the role of fisheries management. Using historical gear-specific fuel use and landings data, we employ scenarios to examine the potential impact that recent changes in the management of the New England fishery for Atlantic herring (Clupea harengus) may have on fishery-related fuel use and greenhouse gas emissions. Specifically, we consider the direct effect of the seasonal ban of midwater trawling in favor of purse seine and fixed gears within Atlantic herring fishing Area 1A. We also evaluate the indirect effect of reductions to the Area 1A total allowable catch of Atlantic herring on the regional supply of bait and the resulting potential need to import bait herring from Canada. Our results indicate that because of the five-fold lower fuel intensity of purse seining, relative to midwater trawling (21 L/ton versus 108-118 L/ton), the seasonal ban on midwater trawling has the potential to markedly reduce overall fuel use and greenhouse gas emissions associated with the herring fishery. These results indicate that management decisions can strongly influence energy demands and resulting greenhouse gas emissions of fisheries. We urge those involved with fisheries management to take this into account when developing policy and management measures. 相似文献
11.
《African Journal of Marine Science》2013,35(1):181-203
Orange roughy Hoplostethus atlanticus are unusual fish. They form dense aggregations that have fuelled lucrative fisheries at great depths (600–1 400 m), especially off Namibia, New Zealand and Australia. They are thought to be very long-lived (>100 years, maturity at 22 – 40 years), and to have exceptionally low natural mortality (M = 0.045–0.064 year?1) and slow growth rates (K = 0.055–0.070 year?1). In addition, they spawn large eggs and have low fecundity. These factors combine to make orange roughy highly susceptible to overfishing; most stocks are below 30% of pristine levels. Assessments are obtained from indices of catch rate and trawl, acoustic and egg surveys. Acoustic estimates are the most direct, but are confounded by the species' low target strength (?50 to ?53 dB)–attributable to the wax-filled swim bladder. Extracellular wax esters are stored in abundance and comprise mostly mono-unsaturated fatty acids, with low concentrations of the ω-3 fatty acid family. This unusual composition (resultant from the species' diet) ensures neutral buoyancy. Stock separation has been inferred mainly from biological studies, but genetic studies have also found differences among stocks within New Zealand and Australia. Deep-water habitat may be damaged by trawling operations and may take many years to recover, so in some quarters there is a call for a portion of suitable habitat to be set aside for preservation. Although Namibian orange roughy are shallower, smaller and younger than those in other stocks, the Namibian fishery sustained high catches for only a few years before quotas were reduced, from 12 000 to 1 875 tons. Three management lessons are suggested for developing orange roughy fisheries based on the Namibian experience: (1) imposition of catch limits during exploratory fishing; (2) starting the acoustic surveys earlier in the fishery, if possible; (3) greater reliance on trends in catch rate until a survey series has been established. 相似文献
12.
Xu Jianping 《海洋学报(英文版)》1992,11(3):343-356
On the basis of the hydrographic data observed within the Canary Basin in autumn 1985, temperature-salinity properties, distributions of water masses and barocltne flow field, as well as the volume transports in this area are described more detailly. The analyses indicate that the activity in the waters of the Canary Basin is mainly attributed to the interleaving and mixing between the originated water masses (e. g. Surface Water, North Atlantic Central Water, Mediterranean Water and Deep Water) and the modified water masses (Subpolar Mode Water, Labrador Sea Water and Antarctic Intermediate Water) from the outside of the study area and the variation of themselves. The east recirculation of the Subtropic Gyre in the North Atlantic consists of Azores Current and Canary Current.Azores Current is formed with several flow branches around the Azores Island, while the main flow lies at 35?N south of the Azores Island. It begins to diverge near the 15?W. The return flow found off the Portugal coast may be its 相似文献
13.
Malcolm R. Clark Ashley A. Rowden 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(9):1540-1554
Seamounts, knolls, pinnacles and other “seamount-like” features are prominent and widely distributed features of the New Zealand marine environment, and also the focus of important commercial fisheries and some exploratory mineral mining. There is considerable debate about the effects of such activities on the benthic habitat of deep-water seamounts. In 2001 a study was undertaken of eight seamount-features on the Chatham Rise, an area that has been heavily trawled for orange roughy since the early 1990s. Half of the study seamounts were considered unfished and the other half fished. Benthic macro-invertebrate assemblages of each seamount were sampled using epibenthic sleds, whilst the presence of habitat-forming fauna (e.g., live corals), substrate type and indications of trawling (e.g., trawl door marks) were determined using a towed underwater camera. Fisheries catch-effort data were examined to determine the amount and distribution of bottom trawling effort on the seamounts. Analyses of camera data revealed that unfished seamounts possessed a relatively large amount of stony coral habitat comprising live Solenosmilia variabilis and Madrepora oculata (predominantly on the seamount peaks) whereas fished seamounts had relatively little coral habitat. Indications of trawling were observed over six times more frequently on seabed images from fished as opposed to unfished seamounts, and appeared related to the amount of fishing effort on individual seamounts. Multivariate analyses of sled data revealed a significant difference in macro-invertebrate assemblage composition between fished and unfished seamounts. The variability observed in assemblage composition between seamounts can in part be explained by the relative fishing pressure measured by a fishing effects index. The results of the study are discussed with respect to management of seamount habitat, and the need for ongoing monitoring and research to derive conservation practices that allow for sustainable seamount fisheries. 相似文献
14.
《Oceanologica Acta》1999,22(6):593-602
Major commercial fisheries for orange roughy (Hoplostethus atlanticus) occur on seamount features, which are widely distributed throughout the New Zealand region. When the fishery developed in the late 1970s to early 1980s, it occurred mainly on flat bottom, but over time has become more focused on seamounts. In the 1995–1996 fishing year, it is estimated that about 70 % of the catch of orange roughy within the New Zealand EEZ was taken from seamounts. Seamounts on the Chatham Rise have been fished for over ten years. Examination of commercial catch and effort data show strong declines in catch rates over time, and a pattern of serial depletion of seamount populations, with the fishery moving progressively eastwards to unfished seamounts along the southern margins of the Rise. Catch rates on seamounts in other regions of New Zealand have also generally shown a similar pattern of rapid decline. There is growing concern over the impact of trawling on seamounts, and the effects this can have on the benthic habitat and fauna, and the long-term sustainability of associated commercial fisheries. 相似文献
15.
《African Journal of Marine Science》2013,35(1):213-217
A good relationship between the variability in measurements of Cape hake Merluccius capensis biomass during winter and summer swept-area research surveys and sea surface temperature off southern Namibia for the years 1983–1990 is presented. The results call into question the hypothesis that hake density is related to biomass and imply that abnormally warm summers could support higher catches, regardless of the state of the stock. A hypothesis that anomalous warm conditions could induce hake to concentrate closer to the sea bed, making them more susceptible to bottom trawling, is presented. 相似文献
16.
Matthew D. Aschaffenburg 《Marine Ecology》2008,29(3):348-353
Indirect interactions are among the many important factors that influence the community structure of the rocky intertidal zone. Trait‐mediated indirect interactions, in which the presence of a predator or competitor can influence the relationship between two other species, have emerged as vital for understanding community dynamics. This study examined the effect of different crab species on the feeding habits of an intertidal snail, Nucella lapillus. Crab species were defined as being sympatric predatory (Carcinus maenas and Cancer irroratus), sympatric non‐predatory (Uca pugnax and Pagurus longicarpus), or allopatric predatory (Mithrax sculptus and Percnon gibbesi). Nucella lapillus were potentially exposed to risk cues from each of the crab species. Crabs were kept in perforated boxes, which allowed any chemical cues to be emitted but prevented direct contact. Nucella lapillus had significantly lower feeding rates in the presence of sympatric predatory crab species than N. lapillus exposed to either sympatric non‐predatory crabs or allopatric predatory crabs. There was no difference in feeding rate between N. lapillus exposed to the sympatric non‐predatory crabs and to the allopatric predatory crabs. Nucella lapillus in the presence of sympatric predatory crabs had a feeding rate of only 0.07 barnacles per snail per day, whereas N. lapillus housed with non‐predatory crabs and allopatric predatory crabs had rates of 0.11 and 0.12, respectively, suggesting that N. lapillus alter their behavior in response to chemical risk cues from local predators. These results suggest that the ability to detect and respond to risk cues is a selectively evolved trait. 相似文献
17.
We collected mesozooplankton samples in the upper 100 m in spring or early summer each year between 1995 and 2000 along a section from Hamilton Bank (Labrador) to Cape Desolation (Greenland), and along additional sections in spring 1997 and early summer 1995. The North Atlantic waters of the central basin were characterised by the presence of the copepods Calanus finmarchicus, Euchaeta norvegica and Scolecithrocella minor and euphausiids. Calanus glacialis, Calanus hyperboreus and Pseudocalanus spp. were associated with the Arctic waters over the shelves. Amongst the other enumerated groups larvaceans were concentrated over the shelves and around the margins. Amphipods, pteropods and the copepods Oithona spp. and Oncaea spp. showed no definable relationships with water masses or bathymetry, while the diel migrant ostracods and chaetognaths were confined to deep water. Metrida longa, also a strong diel migrant, and Microcalanus spp., a mainly deep water species and possible diel migrant, were both sometimes quite abundant on the shelves as well as in the central basin, consistent with their likely Arctic origins.Analysis of community structure along the section across the Labrador Sea indicated that stations could be grouped into five different zones corresponding to: the Labrador Shelf; the Labrador Slope; the western and central Labrador Sea; the eastern Labrador Sea and Greenland Slope; and, the Greenland Shelf. The boundaries between zones varied spatially between years, but community composition was relatively consistent within a given zone and a given season (spring versus early summer). The relationship between community composition and water masses was not entirely straightforward. For example, Labrador Shelf water was generally confined to the shelf, but in spring 2000 when it also dominated the adjacent slope zone, the community in the Labrador Slope zone was similar to those found in other years. Conversely, in spring 1997, when Arctic organisms were unusually abundant in the Labrador Slope zone, there was no increased contribution of shelf water. In addition, North Atlantic organisms were often found on the shelves when no slope or central basin water was present.Although other organisms were sometimes very abundant, the mesozooplankton preserved dry weight biomass was dominated everywhere by the three species of Calanus, which together always accounted for ≥70%. One species, C. finmarchicus, comprised >60% of the total mesozooplankton biomass and >80% of the abundance of large copepods in spring and summer throughout the central Labrador Sea. In western and central regions of the central basin average C. finmarchicus biomass was ca 4 g dry weight m−2 and average abundance, ca 17?000 m−2 over both seasons. Highest levels (ca 7 g dry weight m−2, >100?000 m−2) occurred in the northern Labrador Sea in spring and in eastern and southwest regions in early summer. C. hyperboreus contributed ca 20% of the total mesozooplankton biomass in the central basin in spring and <5% in early summer, while C. glacialis accounted for <1%. Over the shelves, C. hyperboreus contributed a maximum of 54% and 3.6 g dry weight m−2, and C. glacialis, a maximum of 29% and 1 g dry weight m−2, to the total mesozooplankton biomass. 相似文献
18.
J. S. Burgess 《新西兰海洋与淡水研究杂志》2013,47(3):551-553
Examination of bacteriological, water pollution in river and nearshore ocean waters of southern Hawke Bay suggests that presentation and analysis of data expressed in terms of the median, as stipulated by New Zealand water pollution legislation, is often unsatisfactory. Data distributions are non‐normal and statistical comparisons over time and area difficult. These difficulties can be largely overcome by a simple log transformation of data. 相似文献
19.
O. David Mirera 《Ocean & Coastal Management》2011,54(11):844-855
Mud crab (Scylla serrata) is a delicacy for subsistence consumption in fisher communities and tourist hotels in the coast of Kenya while export demand to markets in China and Japan is expanding and provides competitively higher prices. Crab exploitation and degradation of the mangrove forests have increased over the last decades therefore threatening the capture fishery. The preferred market size crab has consistently decreased from more than 1 kg two decades ago to the current size of 0.5 kg therefore posing both management and livelihood threat to the critical ecosystem (mangrove) and coastal populations. To meet the increased tourist and export demand and provide surplus for the local community while conserving the critical crab ecosystem, small-scale aquaculture has been initiated in the concept of silvofisheries. Initial culture methods have targeted sub-adult crabs of 150–350 g for culture to market size (>0.5 kg) in drive-in cages and pens (mud crab fattening). These technology attained survival of between 50 and 70% and a market price of 5 dollars per kilogram. However, research is ongoing to assess viability of stocking juvenile seed crabs directly in ponds as practised in South East Asia (SEA) as opposed to stocking of sub-adults in drive-in cages. In comparison with other areas, crab capture fisheries in East Africa have limited management and enforcement frameworks/capabilities within the wider regional fisheries policies. Also there is limited understanding of wild mud crab resources and suitable management options to avoid over-exploitation as observed in SEA. The double-edged demand (wild market size capture and juvenile capture for aquaculture) for mud crabs in addition to mangrove degradation are likely to cause great challenges to stock exploitation and livelihoods of the coastal people dependent on the resource. This review paper provides an inside onto the tradition, trends and options for development of mud crab capture and culture in Kenya. 相似文献
20.
《Marine Policy》2015
Neoliberal economic and social policies during the last 65 years have placed a premium on continuous economic growth. Concern among ecological economists and other critics that economic growth results in loss of natural capital and ecosystem services led to introduction of the concept of “uneconomic growth,” defined as “growth of the macro economy that costs us more than it is worth” (Daly and Farley, Ecological economics principles and applications. Washington: Island Press; 2004). This paper proposes the concept of “unjust uneconomic growth” to pinpoint the additional costs of policies that promote uneconomic growth to the neglect of other considerations and uses the case of Newfoundland and Labrador fisheries policies since 1992 to document it. Newfoundland and Labrador fisheries experienced uneconomic growth in the 1980s leading to the collapse of ground fish stocks. The policies enacted since 1993 based on economic growth goals have failed to solve the ecological-social crisis and entailed additional costs to small-scale fisheries. 相似文献