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21.
Spatial variability can confound accurate estimates of catch per unit effort (CPUE), especially in highly migratory species. The incorporation of spatial structure into fishery stock assessment models should ultimately improve forecasts of stock biomass. Here, we describe a nonlinear time series model for producing spatially explicit forecasts of CPUE that does not require ancillary environmental or demographic data, or specification of a model functional form. We demonstrate this method using spatially resolved (1° × 1° cells) CPUE time series of North Pacific albacore in the California Current System. The spatial model is highly significant (P < 0.00001) and outperforms two spatial null models. We then create a spatial forecast map for years beyond the range of data. Such approaches can guide spatial management of resources and provide a complement to more data‐intensive, highly parameterized population dynamics and ecosystem models currently in use. 相似文献
22.
The relationships between surface area, stocking density and fish yield in 40 small reservoirs in India between 1994 and 1999 were examined. A significant positive correlation (r = 0.6) was found between stocking density and fish yield. Area was negatively correlated with stocking density (r = ?0.57) and fish yield (r = ?0.62), but its correlation with efficiency of stocking was not significant for all the size groups of small reservoirs. 相似文献
23.
《Human Dimensions of Wildlife》2012,17(4):233-246
Coastal management institutions and recreational fishermen share concerns about the current state of marine fisheries. This article provides coastal managers with an outreach framework for recreational fishers that contextualizes social and ecosystem information toward the goals of ecosystem-based management. Based on a survey of anglers conducted at saltwater fishing expositions in the Northeast United States and on the literature, we report data on perceptions of recreational anglers about potential threats, individual fishing impacts, preferred modes of communication, conceptions, and behavior. We conclude that outreach campaigns should (a) focus on the perceived threats to the resource, (b) contextualize and justify the recommended pro-ecological target behaviors, (c) include topics of general interest to anglers, and (d) communicate through socially trusted sources. 相似文献
24.
Ellie-Ann Conneely;Christopher J. Coates; 《Fish and Fisheries》2024,25(1):134-150
Decapod crustacean welfare is not only an ethical consideration for legislative purposes. Under culture and fishery settings, poor environmental conditions and operator practices can cause stress, which compromises the immune system and increases the risk of disease. For finfish, there are established environmental and animal (group, individual) welfare indicators. This is not the case for crabs, lobsters or shrimp. While environment-based indicators like temperature, pH and oxygen levels are easily transferable, there is no consensus for a common measure of stress to monitor welfare in decapod crustaceans. To address this shortcoming, we conducted a meta-analysis of the primary literature to test for relationships between haemolymph (blood) condition, for example, levels of glucose, L-lactate, haemocytes (n = 8), and sources of physical stress, for example, handling, trawling, emersion and transport (n = 12). Despite variations in effect sizes (n = 459), generalised linear mixed models repeatedly ranked L-lactate (followed by urea and glucose) as the most significant physiological predictor of stress in the haemolymph, with trawling followed closely by emersion as the most impactful stressors. Duration post (stress) exposure, sex (male, female), water temperature and moult stage (pre-, inter-, post-moult) were not associated significantly with stress prediction using the selected biochemical and cellular parameters, however, moult status was undefined in ~48% of literature sources and should be interpreted with caution. We present evidence that quantitating L-lactate levels in the haemolymph represents a physiologic operational welfare indicator of decapod crustaceans, which complements existing condition/vigour indices. 相似文献
25.
《水产资源保护:海洋与淡水生态系统》2018,28(1):146-157
- Large declines in reef fish populations in Hawai ‘ i have raised concerns about the sustainability of these resources, and the ecosystem as a whole. To help elucidate the reasons behind these declines, a comprehensive examination of reef fish assemblages was conducted across the entire 2500 km Hawaiian Archipelago.
- Twenty‐five datasets were compiled, representing >25 000 individual surveys conducted throughout Hawai ‘ i since 2000. To account for overall differences in survey methods, conversion factors were created to standardize among methods.
- Comparisons of major targeted resource species (N = 35) between the densely populated main (MHI) and remote north‐western Hawaiian Islands (NWHI) revealed that 40% of these species had biomass in the MHI below 25% of NWHI levels. In total, 54% of the species examined had biomass <50% of NWHI biomass.
- The moku or district was a basic unit of resource management in pre‐contact Hawai ‘ i and was used as a unit of spatial stratification for comparisons within the MHI. Biomass of resource species was negatively correlated with human population density within moku boundaries, with extremely low biomass in areas with highest human population densities. No such relationship was found for species not targeted by fishing.
- A number of remote areas with small human populations in the MHI still support high standing stock of fished species, and these areas are likely important refugia for maintaining fisheries production and biodiversity functioning.
- These results highlight the large gradient of human impacts on fish assemblages across the Hawaiian Archipelago and the potential in using landscape and seascape units, such as those that are watershed and bio‐physically‐based, when managing in part based on a framework of traditional ecological knowledge.
26.
A substantial amount of scientific effort goes into understanding and measuring compliance in fisheries. Understanding why, how and when fishers follow or violate rules is crucial for designing effective fishery policies that can halt overfishing. Non‐compliance was initially explained almost exclusively with reference to economic and self‐interested motivations. More recently, however, most explanations involve a combination of economic, social, political and environmental factors. Despite this recent development towards more holistic explanations, many scientists continue to frame the issue in binary terms: fishers either follow rules, or they don't. In this article we challenge this binary interpretation and focus attention on the diversity of fishers’ dispositions and perceptions that underpin compliant behaviour. To this aim we construct a typology of fishers’ responses towards regulation and authorities, thereby developing conceptual tools to understand different motivations and attitudes that underlie compliance outcomes. For this purpose, we identify the motivational postures of ‘creativity’ and ‘reluctance’, and then highlight their empirical relevance with an interview study of Swedish fishers. Reasons for studying the quality and diversity of fishers’ motivations and responses are not purely academic. Conceptualizing and observing the quality of compliance can help policymakers and managers gauge and anticipate the potentiality of non‐compliant fishing practices that may threaten the resilience of marine ecosystems. 相似文献
27.
运用偏离份额模型,以全国为参考大区,分析了1993-2012年山东半岛蓝区海洋渔业的份额分量N、竞争力偏离分量P、结构偏离分量D。研究结果表明,蓝区海洋渔业仍处于结构演进的"一、二、三"起步阶段:第一产业比重稳步下降,但其中海洋捕捞所占比重依然过大;第二产业比重逐步提高,但产业内部结构存在调整空间;第三产业发展缓慢,缺乏竞争力。根据上述问题,建议通过坚持"以养为主"方针,优化海洋捕捞生产结构,加快发展水产品后续深度加工工业,稳步推进第三产业发展,最终实现海洋渔业产业结构优化。 相似文献
28.
Growth is an important metric in fisheries and aquaculture. Growth of small fish over relatively short periods of time is commonly modelled with an exponential function using instantaneous growth rate (g). Instantaneous growth rates are logarithmic and inherently difficult to interpret, but specific growth rates (SGR) express growth as the intuitively understandable per cent change in size per unit of time. A simple metric of SGR (G) is easily computed by exponentiating g, subtracting 1 and multiplying by 100. However, several prominent fisheries publications suggest that SGR should be calculated by simply multiplying g by 100 (we call this G*). A search of the fisheries literature found that the number of papers that used SGR for fish increased significantly from 1830 papers in 2009 to 3170 papers in 2018. An extensive review of 300 papers from this search found that 92.6% were related to aquaculture and only 3.3% of all papers correctly used G to calculate SGR. We algebraically show that G* is fundamentally different than G and cannot be interpreted as a per cent change in weight per unit of time. Furthermore we demonstrate, with three examples from the literature, that using G* as if it were the same as G leads to biologically meaningful underestimates of true growth rates and estimated weights. Given these results and the simplicity with which G can be computed from g, we recommend that fisheries scientists abandon the pervasive practice of incorrectly measuring SGR as 100 times the instantaneous growth rate. 相似文献
29.
S. J. NEWMAN M. B. PEMBER B. M. ROME G. E. A. MITSOPOULOS C. L. SKEPPER Q. ALLSOP T. SAUNDERS A. C. BALLAGH L. VAN HERWERDEN R. N. GARRETT N. A. GRIBBLE J. M. STAPLEY J. J. MEEUWIG B. R. MOORE D. J. WELCH 《Fisheries Management and Ecology》2011,18(3):246-257
Abstract Stable isotopes of δ18O and δ13C in sagittal otolith carbonates were used to determine the stock structure of the polynemid Eleutheronema tetradactylum (Shaw) across tropical northern Australia, where this species is an important component of inshore commercial and recreational fisheries. Stable isotopes from the sagittal otolith carbonate of 470 fish from 11 discrete locations across western, northern and eastern Australia were sampled between 2007 and 2009. Analysis of these stable isotopes revealed different location‐specific signatures, indicating strong population subdivision. The significant differences in the isotopic signatures of E. tetradactylum demonstrated that there is unlikely to be substantial movement of fish between these locations. The spatial separation of these populations indicates a complex fine spatial scale stock structure across northern Australia, with at least 11 stocks or management units present. The population subdivision of E. tetradactylum was evident along expansive stretches of open beach systems and within coastal embayments with no physical barriers such as headlands. These results indicate that optimal fisheries management will require a review of the current spatial arrangements, particularly the potential for localised depletion of stocks on small spatial scales. 相似文献
30.
MICHAEL BAUMANN 《Fisheries Oceanography》1998,7(1):63-65
In this paper I discuss some of the shortcomings of today's marine science in response to a recently published paper by Ann Gargett (1997). Three problem areas have been identified in the field linking climate forcing and fish production: First, the yet-to-be established observational proof for a relationship between the two; Second, the strongly neglected biology of organisms at evolutionary and ecological time scales; and thrird, the disregard for spatial and temporal scales in the discussion of mechanisms and supporting data. 相似文献