A collaborative approach to investigate site fidelity, home range, and homing behavior of cabezon (Scorpaenichthys marmoratus)

Understanding the area use requirements of species targeted for protection by marine protected areas (MPAs) is critical to the future conservation efforts of economically important fish species. Knowledge of home range size and site fidelity is essential in determining whether species will benefit from the protection offered by a MPA, the size of the area needed to protect individuals, and the extent to which surrounding unprotected areas may be supplemented through post-recruitment movement or “spillover”. We utilized a traditional mark and recapture approach, along with GIS spatial analysis to investigate the site fidelity, home range, and homing behavior of the economically important fish species cabezon (Scorpaenichthys marmoratus) on the south central coast of California. In collaboration with members of the commercial live-fish fishery, a total of 1240 sub-adult and adult cabezon were tagged during 10 days of fishing from September to December of 2004 along ∼18 km of coastline. A public awareness and reward program resulted in 330 total recaptures from 290 different individuals (23% recapture rate) with recaptured individuals at liberty up to 1000 days after initial tagging. A majority of individuals displayed high site fidelity, with 81% of recapture events occurring within 100 m of their initial capture locations, and only 9 individuals (.03%) recaptured greater than 1 km. Most individuals (64%) displayed home ranges less than 1000 m². Ten individuals recaptured after experiencing translocation of up to 5.3 km displayed strong homing behavior, returning to within 14 m of their initial capture locations. Findings suggest that under circumstances where suitable habitat is available in nearby unprotected areas, that adult “spillover” will likely be limited to areas within 100 m from MPA boundaries. In addition, the size of the area needed to protect individual cabezon, should be at least 1000 m². Findings from this study demonstrate many of the potential benefits of scientists and fishers working together to investigate area use patterns of economically important fish species to facilitate future design and assessment of MPAs.     

Polymorphic mountain whitefish (Prosopium williamsoni) in a coastal riverscape: size class assemblages,distribution, and habitat associations

We compared the assemblage structure, spatial distributions, and habitat associations of mountain whitefish (Prosopium williamsoni) morphotypes and size classes. We hypothesised that morphotypes would have different spatial distributions and would be associated with different habitat features based on feeding behaviour and diet. Spatially continuous sampling was conducted over a broad extent (29 km) in the Calawah River, WA (USA). Whitefish were enumerated via snorkelling in three size classes: small (10–29 cm), medium (30–49 cm), and large (≥50 cm). We identified morphotypes based on head and snout morphology: a pinocchio form that had an elongated snout and a normal form with a blunted snout. Large size classes of both morphotypes were distributed downstream of small and medium size classes, and normal whitefish were distributed downstream of pinocchio whitefish. Ordination of whitefish assemblages with nonmetric multidimensional scaling revealed that normal whitefish size classes were associated with higher gradient and depth, whereas pinocchio whitefish size classes were positively associated with pool area, distance upstream, and depth. Reach‐scale generalised additive models indicated that normal whitefish relative density was associated with larger substrate size in downstream reaches (R² = 0.64), and pinocchio whitefish were associated with greater stream depth in the reaches farther upstream (R² = 0.87). These results suggest broad‐scale spatial segregation (1–10 km), particularly between larger and more phenotypically extreme individuals. These results provide the first perspective on spatial distributions and habitat relationships of polymorphic mountain whitefish.     

Site‐fidelity and movement patterns of bottlenose dolphins (Tursiops truncatus) in central Argentina: essential information for effective conservation

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Spatial and quantitative patterns of movement in large bull trout (Salvelinus confluentus) from a watershed in north-western British Columbia, Canada, are due to habitat selection and not differences in life history

Abstract –  Movement and habitat use by bull trout ( Salvelinus confluentus ) was examined using radio telemetry in the Morice River watershed, north-western British Columbia, between April 2000 and November 2001. Bull trout principally utilised mainstem habitat. Throughout the watershed, little movement was observed during the winter months. From June to September, movement increased and was correlated with migration into tributaries. We directly observed spawning bull trout only in tributaries of the Morice River and never in the mainstem. Many of the fish ( N  = 48) migrated to the nearest potential spawning sites, but a few fish ( N  = 7) made extensive migrations to other regions of the watershed to spawn. Fish that spawned in both years of the study returned to the same spawning location. Variation in spatial and movement data, therefore, appears to be linked to availability of suitable habitat and not differences in life history that have been observed in large bull trout.     

Preliminary telemetry data on the movement patterns and habitat use of European catfish (Silurus glanis) in a reservoir of the River Ebro, Spain

Abstract –  Knowledge of the movements and diel behaviour of the European catfish ( Silurus glanis ), the largest European freshwater fish, is limited to anecdotal information. In a preliminary telemetry study of European catfish, the spring diel movement patterns of five adult catfish were examined. After intraperitoneal insertion of the acoustic tags, the positions of the fish were recorded automatically in the Flix Reservoir (River Ebro, NE Spain). A marked nocturnal mobility pattern was observed throughout the study. During daytime, the catfish were consistently located in the littoral zone and spent extended periods of the day hidden in concealed habitats. Catfish movements were in a radial pattern, with upstream and downstream excursions followed by returns to a previously occupied location. Significant individual variations in movement pattern were observed among the tagged fish and within the 24 h cycle for each fish. Mean instantaneous swimming speed was 0.17 body lengths per second (BL·s⁻¹) at night but 0.09 BL·s⁻¹ during the daytime.     

Stock structure and seasonal distribution patterns of American lobster, Homarus americanus, inferred through movement analyses

Movement influences the annual distribution patterns of a species and is an important determinant of stock structure. In situations where monitoring programs have quantified movement or distribution patterns by sampling during particular times of the year, seasonal changes in abundance as well as the degree of connectivity among adjacent stocks can be underestimated. Here, a summer abundance trawl survey was combined with a 1-year mark-recapture tagging study to infer seasonal changes in distribution within and among American lobster (Homarus americanus) stocks. Within the study area, lobsters were concentrated in central Northumberland Strait (Canada) during August, yet their observed dispersal behaviour implied that density declined in the central portion and increased in the northern portion of Northumberland Strait during winter. Stock mixing among management zones was not observed and individual tendencies to move were predicted to decline precipitously in early December. These movement patterns are consistent with the hypothesis of seasonal limitation by hard-substrate habitat availability causing population redistribution. Such information can ultimately be useful when assessing changes in abundance or exploitation rates, and for guiding management efforts.     

Site fidelity and movement patterns of wild subadult red drum, Sciaenops ocellatus (Linnaeus), within a salt marsh-dominated estuarine landscape

Abstract  During summer and autumn 2002, 12 subadult red drum, Sciaenops ocellatus (Linnaeus) (261–385 mm total length) were surgically implanted with ultrasonic transmitters and released within the upper reach of the Duplin River Estuary, Sapelo Island, GA, USA. A fixed array of submerged receivers automatically recorded the time that individual tagged fish were detected at 10 sites within the study area. Ten red drum implanted with transmitters were located within the receiver array for 6–96 days post-release. All fish exhibited a high degree of site fidelity at low tide, and movements appeared to be influenced by both tidal and diel cycles. Dispersal on flood tides was observed, but destinations (upriver or downriver) and paths taken (main channel, intertidal channels or flooded marsh surface) varied among individuals. Flood-tide movements were generally restricted to daylight hours. If the start of flood tide occurred after sunset, fish remained stationary. Variation in details of movement patterns among individuals notwithstanding, predictable behaviour and strong site fidelity make subadult red drum vulnerable to recreational fishing in the restricted tidal channels of the tidal marsh–estuary complex. However, the same predictability provides fisheries managers a means of targeting specific areas for protection of over-fished populations of this species.     

Site fidelity,diel and seasonal activities of yellow‐phase Japanese eels (Anguilla japonica) in a freshwater habitat as inferred from acoustic telemetry

Japanese eels (Anguilla japonica) perform large‐scale oceanic migrations between their spawning ground and growth habitats in continental waters during life history. However, between these migrations, they spend most of time in growth habitats such as rivers. To investigate the diel and seasonal activities, homing behaviour and home range of yellow‐phase Japanese eels in the lower reach of the Tone River, we tracked them throughout a year using a fine‐scale positioning system (VPS) based on acoustic telemetry. The tracked eels were generally nocturnal, but not exclusively. They were mainly mobile from spring to autumn, with little or no activity observed during winter. A transport‐release experiment showed that most eels returned to their original capture area within 13 days after release. The eels had very small home ranges (mean ± SD = 0.085 ± 0.068 km²), core areas (0.014 ± 0.014 km²) and linear home ranges (744 ± 268 m). They also tended to be distributed on one particular side of the river (right or left bank) and in one particular shore type (revetment or vegetation), rarely moving from one to the other. This study provides evidence for nocturnal, dormancy, homing behaviours, limited habitat use and small home range size in Japanese eels. The eels clearly showed strong fidelity to a “familiar” site, which contrasts with the long distances travelled during upstream and downstream migration phases in the river, and during spawning migrations in the ocean.     

Size isn't everything: movements,home range,and habitat preferences of eastern blue gropers (Achoerodus viridis) demonstrate the efficacy of a small marine reserve

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2015—2018年珠江口近岸海域鱼类群落结构及其稳定性

探究珠江河口洄游性鱼类凤鲚 (Coilia mystus) 的生境适宜度,可为其渔业资源保护和利用提供科学依据。根据2019年冬季和2020年夏季在珠江河口进行的底拖网调查数据,选取水深、底层盐度、底层水温、底层溶解氧等作为指示因子,利用层次分析法 (Analytic hierarchy process, AHP) 计算各指示因子的权重,采用算数平均法 (Arithmetic Mean Model, AMM) 和几何平均法 (Geometric Mean Model, GMM) 计算栖息地适宜度指数 (Habitat Suitability Index, HSI),验证发现基于GMM且赋予权重的HSI模型精确度较高,能较好地反映珠江河口凤鲚的栖息地分布。最优模型结果显示,珠江河口冬季和夏季凤鲚适宜的底层盐度分别为21.03‰~30.55‰和20.25‰~25.82‰,溶解氧质量浓度分别为6.79~7.28和3.85~4.01 mg·L⁻¹,水深分别为11.69~20.10和7.80~9.23 m,底层水温分别为19.84~19.95和28.36~29.44 ℃。珠江河口凤鲚HSI大于0.5的站点仅占总调查站点的17.39%,表明其栖息地适宜性较低,目前珠江河口适宜凤鲚的栖息地主要位于内伶仃海域的中华白海豚自然保护区。     

中华绒螯蟹幼体的栖息生境选择与行为特征

为探究中华绒螯蟹在早期发育阶段对不同栖息生境的选择偏好及其行为特征，实验以长江口近岸微生境类型为基础，在室内建立了藨草、泥底、铁板沙、砾石等4种模拟生境，选取中华绒螯蟹大眼幼体、Ⅰ、Ⅲ、Ⅴ期仔蟹分别开展了对不同生境选择的行为观察和定量分析。结果显示，中华绒螯蟹大眼幼体、Ⅰ、Ⅲ、Ⅴ期仔蟹在藨草生境中分布比例最高，显著高于其他三种生境。随着仔蟹的生长发育，Ⅲ、Ⅴ期仔蟹在泥底和铁板沙生境中占比增大。在藨草生境中，中华绒螯蟹幼体具有游泳、附着藨草、表栖、埋栖等4种行为，大眼幼体和Ⅰ期仔蟹主要表现为附着藨草行为，Ⅲ期仔蟹的表栖、埋栖行为显著增加。幼体在藨草生境中的蜕壳率显著高于泥生境，而死亡率显著低于泥生境。研究表明，中华绒螯蟹幼体偏好栖息于有利于其生存、发育的藨草等植被生境中，这可能与藨草等植被生境为中华绒螯蟹幼体提供了适宜的庇护场所有关。本研究结果指出了植被生境对中华绒螯蟹幼体阶段的重要性，丰富了早期生活史资料，并为其资源保护和栖息地生态修复提供了基础参考。     

Change in habitat associations and geographic distribution of thorny skate (Amblyraja radiata) in the southern Gulf of St Lawrence: density‐dependent habitat selection or response to environmental change?

We describe changes in the habitat associations and geographic distribution of thorny skate during their feeding season in the southern Gulf of St Lawrence, based on 32 yr of monitoring by a bottom‐trawl survey. In the 1990s, geographic range contracted sharply and distribution shifted into a narrow band of warm deep waters. These changes appeared to reflect altered habitat selection by individual skates, rather than local depletion of the skates that had habitually occupied the vacated areas or a change in the timing of seasonal migrations. Changes in skate distribution coincided with a decline in skate biomass and a cooling of bottom waters. The contraction in the geographic range of skates appeared to be a density‐dependent response, more closely linked to the decline in skate abundance than to the change in environmental conditions. The cause of the shift in habitat associations is less certain. An index of the distribution shift was more strongly correlated with skate biomass than with an index of temperature conditions, and the change in temperature associations is in the direction predicted by density‐dependent bioenergetic considerations. However, the shift into deeper waters is into a depth zone where skate condition is relatively low, contrary to the expectation that fish should be concentrated in optimal habitat at low population size. On the other hand, while the shift into warm deep waters coincided with a cooling of waters at intermediate depths, distribution failed to shift back to the earlier pattern as these waters warmed in the late 1990s.     

Spatial and temporal distribution and abundance of European hake, Merluccius merluccius, eggs and larvae in the Catalan coast (NW Mediterranean)

Plankton hauls were conducted on five surveys from November 1998 to November 1999 to study the spatial distribution of eggs and larvae of European hake off Catalonia (NW Mediterranean Sea). Also CTD casts to record hydrographic parameters were carried out on a closely spaced station grid. Merluccius merluccius eggs and larvae appeared mainly in late spring, summer and autumn surveys and were very scarce in winter. Strong differences in terms of egg and larval densities were observed between the two November surveys, which could be attributed to the anomalous hydrographic situation during November 1998. M. merluccius egg and larvae were mainly distributed over the continental shelf, with peak abundances between the 100 m isobath and the edge of the shelf. On the evidence of larval size frequency distributions in the different sampling sectors and the closely overlapping distribution patterns for the eggs and the adult spawning stock, drifting of hake eggs and larvae was not a major factor. The larval distribution extended only slightly further offshore than the egg distribution. Using the hydrographic information and the larval distribution data, an attempt was made to relate the different seasonal productivity levels over the spawning period and the distribution of the larvae.     

秀丽白虾4种C型凝集素基因的克隆、组织表达与进化分析

C型凝集素是一类Ca² 依赖活性的糖蛋白,在虾蟹类的免疫防御中发挥着重要作用。采用RT-PCR及RACE技术首次克隆了秀丽白虾C型凝集素家族4个基因( EmCTL-1、EmCTL-2、EmCTL-3、EmCTL-4)的cDNA全长。这4个C型凝集素基因的cDNA全长分别为1 390、1 119、1 364和1 299 bp,分别含996、969、 1 026和1 044 bp的开放阅读框,各编码332、322、341和347个氨基酸的蛋白。其氨基酸序列与罗氏沼虾相应的C型凝集素的相似性分别为40%、37%、69%和73%, 与其他海水虾类的相似性在30%～41%之间。阳性选择模型分析显示虾类的C型凝集素基因在进化过程中经历了阳性选择。进化树分析表明,秀丽白虾的 C型凝集素基因与罗氏沼虾的亲缘关系最近,并且除EmCTL-4属于十足类C型凝集素亚群A外,其他均属于亚群C。组织表达分析表明,EmCTL-1主要在血液中表 达,EmCTL-2主要在性腺、血液和胸神经节中表达,而EmCTL-3和EmCTL-4则主要在精巢中表达。研究表明,秀丽白虾的C型凝集素基因具有较快的 进化特点,同时又具备凝集素行使免疫功能时必需的保守氨基酸残基及钙离子结合位点,精巢和血液是秀丽白虾C型凝集素基因主要的表达器官。     

Effect of population structure, sampling strategy and sample size on the estimates of selection parameters for shrimp (Crangon crangon) trawls

In selectivity experiments with shrimp trawls, very high numbers of animals in the catches of single hauls are a common feature and therefore, sub-sampling is inevitable. In order to find an acceptable balance between work-load and accuracy in the estimation of the selection parameters, it is important to have a sensible idea on the minimum numbers of shrimps to be measured in each catch fraction (cover, discards and landings). The present theoretical study tries to answer this question by means of computer simulations of different sampling strategies and sample sizes applied to catches with known size compositions.

The results of the simulations are discussed in relation to population structure, shape of the cod-end selection curve, sampling strategy (as the relative amounts measured from the different catch fractions) and sample size, and the method used to calculate the selection parameters.

Samples of 750 animals provide an acceptable compromise between work-load and reliability of the estimated selection parameters, provided that sufficient numbers of length classes are available. Population structure, selection curve and sample size (in that order) largely determine the reliability of the estimates, whereas the sampling strategy, on the other hand, only has a minor effect.