Tagged Lobsters Research Articles

Pop-up satellite archival tags and an individual-based model provide new insights on behavioural thermoregulation in migrating ovigerous American lobster

Ovigerous American lobsters, Homarus americanus, in the Bay of Fundy undertake seasonal migrations, which are thought to improve the thermal conditions experienced by their embryos. However, the complete thermal and bathymetric history of such females has never been characterized. To this end, we deployed pop-up satellite archival tags on two ovigerous females (160 mm carapace length) in the Bay of Fundy between September 2013 and July 2014. Tagged lobsters traveled from the release location (Grand Manan, New Brunswick) to points near Beaver Harbour, New Brunswick, and Port George, Nova Scotia, representing linear displacements of 33 and 123 km, respectively. Recorded depth and temperature for both lobsters confirm shallow-to-deep migrations in the fall and deep-to-shallow migrations in the spring. The high-resolution, nearly continuous data generated by the satellite tags indicated that local changes in temperature may be the proximate trigger for fall movements, but do not cue movements in spring. We then developed an individual-based model to investigate the mechanisms and thermal outcomes of seasonal migrations, where lobster movements were allowed to vary according to bottom temperature, an individual's level of preference for warmer waters and its scope for movement. This modeling work, combined with the fine-scale thermal and depth history of our tagged lobsters, indicated that the movements our lobster undertook clearly increased, but did not maximize, the temperature their embryos experienced, relative to lobsters moving randomly or not at all. The novel data and modeling approach used in this study shed new light on the nature, trigger and function of seasonal migrations displayed by American lobsters in the Bay of Fundy.

Spatial overlap, proximity, and interaction between lobsters revealed using acoustic telemetry

The cryptic nature ofHomaruslobsters has restricted past behavioural studies to aquaria, mesocosms, or shallow coves. As such, spatial overlap and interactions between free-rangingHomaruslobsters have received little attention. However, it is clear that dominance behaviours directly affect their probability of capture, negatively affecting catch and complicating population monitoring. This study describes lobster behaviour at a scale that could not be achieved in aquaria or mesocosms. Home-range overlap and contact rates among free-ranging, acoustically taggedH. gammarus(n = 44) were assessed at multiple spatial scales. Data were analysed as unique pairings of lobsters (dyads), which could be single- or mixed-sex pairings. If home-range overlap between tagged lobsters occurred, interactions between lobsters were classified as attraction or avoidance. The number of times a lobster overlapped with the home range of another lobster was related to the mean substrate hardness within the home range of the focal lobster. Fewer interactions occurred between female lobsters, compared to males and mixed-sex pairings. Interactions between lobsters that occurred at 10 m, and interactions between mixed-sex pairs at 5 m, were identified as attractions. Interactions between male lobsters at 5 m were largely identified as avoidance and may indicate small-scale spatial exclusion. Understanding the drivers of movement and behaviour in wild free-ranging lobster populations is relevant to stock assessments, disease management, protected areas designation, and the development of sustainable evidence-based fisheries.

Stock structure and connectivity of the American lobster (Homarus americanus) in the southern Gulf of St. Lawrence: Do benthic movements matter?

The long-range dispersal of pelagic larvae is often assumed to be the dominant force behind connectivity in the marine environment, with little consideration given to benthic movements. We analyzed data from an American lobster (Homarus americanus) tagging study (1980–1996) in the Gulf of St. Lawrence during which 37 579 adults from 14 locations were tagged and 6296 were recaptured after 1–6 years at large. The 10th percentile greatest distance moved by tagged lobsters after 1 year at large contributed to demographic connectivity between neighbouring statistical districts, fishing ports, and (in one location) management areas. Considering the incremental dispersal of lobsters after 2 versus 1 year at large, we estimated that the 10th percentile greatest benthic dispersal distances after 1, 2, and 5 years at large represented, respectively, 7%, 14%, and 35% of larval dispersal in the “downstream” direction and 75%, 111%, and 220% of larval dispersal in the “upstream” direction (similar results obtained based on mean dispersal values). We conclude that more attention should be given to benthic movements in estimating connectivity and stock structure in American lobster.

Diel activity and short‐distance movement pattern of the European spiny lobster, Palinurus elephas, acoustically tracked

AbstractThis paper presents the results of the application of an ultrasonic telemetry system to the investigation of short‐term movements in the European spiny lobster, Palinurus elephas, in a coastal area of NW Sicily (Central Mediterranean Sea). Ten lobsters were tagged with miniaturized transmitters and released over a favourable habitat and their movements then recorded by means of nine automated receivers with the objective of investigating post‐release displacement, home‐range extension, movement patterns, activity rhythm and the influence of lunar light intensity on lobster activity. Acoustic detection data were used to assess activity and home range using estimates of horizontal and vertical movements and minimum convex polygons, respectively. Continuous wavelet transform (CWT) analysis was applied to time series of position data. Acoustic data from five of 10 lobsters were successfully recorded across a 78‐day study period between April and June 2008. All of them displayed an activity pattern characterized by diurnal sheltering and nocturnal foraging, with higher activity (i.e., longer distances travelled) at night. Their home range measured between 1629 and 8641 m2, and all lobsters relocated every 4.6 days on average, probably in search of unexploited feeding grounds. For this reason we hypothesize a nomadic movement pattern for our tagged lobsters. CWT analyses highlighted a 24‐h periodicity in lobster activity, with higher activity from sunset to sunrise. No clear influence of moon phase on lobster activity was detected.

Evaluation of coded microwire tag retention in juvenile American lobster, Homarus americanus

The reliability of population dynamics and stock assessment models hinges on accurate life-history information. Mark-recapture studies represent a commonly used technique to investigate crustacean growth, mortality, and migrations. We evaluated tagging by coded microwire tags for the American lobster, Homarus americanus H. Milne Edwards, 1837, in a controlled study to determine tag retention and any influence on growth increment, intermolt duration, or survival. Microwire tags were injected into the propodus of the second right walking leg and two size classes (12-19.6 and 19.7-30 mm carapace length [CL]) were tested by two individual taggers. Overall tag retention was 96%. Tag retention after first ecdysis was 95% for the 12-19.6 mm CL and 92.5% for the 19.7-30 mm CL size class. There was no significant difference in tag retention between taggers, growth between tagged and untagged lobsters, or intermolt duration between tagged and untagged lobsters (P > 0.05 for all tests). Tag-induced mortality did not occur. These results support the further use of coded microwire tags to explore life-history variables for juvenile lobsters in the wild.

Integrating recapture-conditioned movement estimation into spatial stock assessment: A South Australian lobster fishery application

The practical aim of this study was to estimate biomass in two subregions, inshore (<60 m depth) and offshore (>60 m), for application to rock lobster management. To account for lobster movement between these subregions, movement estimation was integrated into the length-structured stock assessment model. Tagged lobsters were released inshore and offshore in the mid-1990s. For fitting to these conventional single tag-recoveries, a recapture-conditioned movement rate estimation method was adapted and integrated into the assessment model. The individually-tailored probabilities of survival during time-at-large and of subsequent capture in each subregion needed to estimate movement rates are provided by the over-arching stock assessment estimator. Calculating a probability specific for each lobster recapture permits the estimator to account for naturally varying times and locations of tag release and recapture. Seasonality of tagged lobster movements indicated that inshore-to-offshore migration occurred predominantly in winter. Yearly movement rates of lobsters were relatively low. Biomass was approximately 3–4 times higher inshore than offshore. Testing using simulated data confirmed the accuracy of model-integrated recapture-conditioned movement estimates. Using these same simulated data, conventional movement rate estimates, calculated as raw proportions of recaptured lobsters that moved, were positively biased. Incorporating survival and recovery rates in movement estimation can thus substantially improve the accuracy of movement, and thus biomass, estimates in spatially-resolved stock assessments.

Movement patterns of the spiny lobster &lt;em&gt;Palinurus elephas&lt;/em&gt; (Fabricius, 1787) from a central western Mediterranean protected area

Movement patterns of the spiny lobster Palinurus elephas were determined from 389 individuals (total tagged 5666) tag-recaptured inside a no-take area of the central western Mediterranean and its surrounding zone. High site association and limited movements in tagged lobsters was observed; 60.4% of lobsters moved less than 2 km from the centre of the area (site of release). No clear relationship between lobster movement pattern and sex or size was observed; however, it seemed that the largest males and females tended to be more resident, thus contributing to the rebuilding of the biomass of local lobsters. Most lobsters undertook migrations in the southwest direction. The increased availability of shelters and food towards the southwest could have contributed to the lobsters’ movement. The results of our research indicate that the small size of the protected area and the scale of the movement exhibited by tagged lobsters allows a proportion of the lobster population to move out of the protected area and become susceptible to capture in the adjacent fishery.

Longshore Movements of Adult Male Jasus Lalandii: Evidence from Long-term Tag Recaptures

Large-scale longshore movements (>10 km) of adult male Jasus lalandii (>70 mm carapace length) were examined on the west coast of South Africa using tag-recapture information from the period 1968 to 2000. The average rate of recovery of tagged rock lobsters was 15.7% per fishing season. Only 0.48% of 43 885 recaptured rock lobsters moved >10 km, 0.31% southwards and 0.17% northwards. The mean distance moved by those lobsters was 28.6 km and the mean time at liberty was 241.8 days. In recent years, densities of J. lalandii have increased substantially at the south-eastern end of their geographic range. The data indicate that this could not be attributable to a population migration of adult male rock lobsters from the west coast of South Africa.

Evaluation of visible implant fluorescent elastomer (VIE) as a tagging technique for spiny lobsters (Jasus edwardsii)

Tagging crustaceans for growth studies is often difficult because external tags/marks may be shed or cause mortalities during moulting. In this investigation, the effectiveness of visible implant fluorescent elastomer (VIE) as an invasive tagging technique for spiny lobsters (Jasus edwardsii) was investigated over a 6-month period. Tagged lobsters were either tagged with the tag running transversely across the ventral abdominal superficial flexor muscle block (transverse VIE) in the second abdominal segment, or in-line with the ventral abdominal superficial flexor muscle block (longitudinal VIE). Non-tagged lobsters were used as the control. At the conclusion of the investigation there were no differences in growth or survival between tagged lobsters and untagged controls and tag retention rates were 100% for both tagging treatments over the 6-month period. Tag visibility was high after six months in both tagging treatments, although higher in the longitudinal VIE treatment. Tag fragmentation was frequent in the transverse VIE treatment, but infrequent in the longitudinal VIE treatment. We conclude that VIE is an effective tagging technique for J. edwardsii in terms of the high degree of tag visibility, retention, and non-detrimental impact on the growth and survival of tagged animals, provided the VIE tag is injected in-line with the orientation of the muscle fibres/tissue.

Seasonality and shelter selection by the slipper lobster Scyllarides latus in the southeastern Mediterranean

Patterns of migration, abundance and shelter selection by Mediterranean slipper lobsters Scyllarides latus were studied in artificial shelters placed on the shallow continental shelf off the coast of Israel. Underwater censuses and tagging experiments over >3 yr indicated a seasonal pattern of adult lobster abundance in shallow water. Lobsters' appearance at the site was associated with low water temperature m winter. They disappeared from shallow water in the study area from mid-summer to late fall. Preliminary data of recaptured tagged lobsters suggest that they migrate northwards and to deeper water. Such long-term migration may be triggered by the high, and perhaps unfavorable, mid-summer temperature in the shallow coastal habitats. It is hypothesized that the continuous stay of slipper lobsters in deeper water through late fall may be a physiolo~cal/behavioral adaptation to molting occurring in this period. During their stay in shallow water lobsters tended to remain in the artificial shelters complex and its vicinity. They dwelt in shelters during the day and foraged at night, mainly for bivalves, of which some were brought back to dens before daylight. Analysis of lobster recruitment to artificial reefs of different design indicated preference for lower, horizontal dens with small apertures. Habitats rich w i t h such she!ters arc very limited aiong the ilat bottoms of the littoral southeastern Mediterranean. Since sheltering in such dens presumably reduces the risk of predation by diurnal predators, it is advantageous for lobsters to return to these preferred sites after short as well as long-term movements.

An electromagnetic tracking system for use in shallow water

Modifications to an electromagnetic method of tracking juvenile western rock lobsters Panulirus cygnus George are documented. The receiving aerials were made more robust to increase their useful life, and an automated tracking system was developed. The system continuously collects data on the movements of up to 14 tagged lobsters simultaneously. The feasibility of the method and its problems are discussed and suggestions are made for its improvement. The susceptibility to wave action of the aerials and the main communication cable that brings the signals to shore suggest that electromagnetic tracking is feasible only in calm and shallow environments.

A quantitative study of nocturnal foraging distances of the western rock lobster Panulirus cygnus George

An electromagnetic tracking device was used to study the distances over which juvenile western rock lobsters Panulirus cygnus George forage at night. Up to 14 tagged lobsters were tracked continuously for up to 3 wk with the aid of an automatic tracking system. A total of 460 “lobster nights” (data on one lobster for 1 night) was recorded during the study. On 48 of these “lobster nights”, the lobsters did not forage. Approximately half of the remaining data were incomplete or “censored” due to lobsters moving outside the tracking area for part of the night. A Weibull distribution showed an extremely close fit to the data after adjustment for the bias of censoring. Through analyses of deviance, comparisons were made of the effect on distance travelled of sampling time, sex, and time since tagging in a way that was analogous to an analysis of variance. The results of the study indicate that nocturnal foraging distances were variable: 95% of the population covered between 72.5 and 585 m · night −1. These distances, which are much greater than previously reported, show that the animals have an unexpectedly large foraging area. The effect on survival of P. cygnus of limited food supply due to small foraging distances may not be as important as previously believed.

Evidence of Migration and Homing of Lobsters (Homarus americanus) on the Scotian Shelf

In the Browns Bank region of the Scotian Shelf between June 1982 and December 1983, 6285 tagged lobsters (Homarus americanus) were released. Of the 2486 lobsters recaptured, 361 were recaptured more than once. Eight lobsters released in late May to mid-July were recaptured the following spring and summer, with at least one intervening recapture in the fall–winter period. Five of the eight lobsters showed homing tendencies. Two lobsters made long-distance (&gt; 200 km) return migrations, three made short (50–100 km) return migrations, and three moved long distances but did not return. One lobster at large 6 mo and four at large 22–34 mo made long-distance return migrations, moving over 200 km and returning to within 9–42 km of the initial release site. The data indicate that some lobsters undertake long-distance return migration, which returns the lobsters to specific sections of the Shelf.

Mortality estimates for the rock lobster,Jasus edwardsii, near Gisborne, New Zealand

The instantaneous total (Z) and fishing (F) mortality rates were estimated for the New Zealand rock lobster, Jasus edwardsii (Hutton), along the east coast of the North Island from the Wairoa River to East Cape. Estimates of Z were made from the seasonal size‐frequency distributions (SFDs) of rock lobsters landed from five separate fishing areas for up to five fishing seasons using three different methods. Z and F were also estimated from the rate of return of tagged rock lobsters released in four of the five areas. The best estimates of Z and F for each area were considered to be estimates of F based on tag returns grouped quarterly and taken over an 8 or 9 month fishing season; estimates of Z based on these estimates of F from tag returns, with the addition of an assumed value for the annual instantaneous natural mortality rate of 0.10; and estimates of Z from the SFD analyses. These estimates were more consistent with the estimated lifespans in the fishery than were the estimates of Z derived from tag ...

Retention of Marks and Their Effects on Growth, Behavior, and Migrations of the American lobster, Homarus americanus

Abstract Laboratory and field experiments were conducted with the lobster, Homarus americanus, to test the retention through molting of three primary marks—the back tag, elbow tag, and brand. Relatively more back tags were retained through the molt than elbow tags or brands. Molestation among tagged lobsters contributed significantly to tag loss. In November 1965 and July 1966, a total of 1776 lobsters were tagged and released at Monhegan Island, Maine. Lobsters were given a primary mark plus a secondary mark of amputated abdominal scutes and spines. The secondary mark was retained through 2 molts and permitted recognition of a lobster that had lost its primary mark. The recapture of marked lobsters through June 1968 yielded information on tag retention and the effects of marks on growth and behavior. Lobsters marked with the back tags had an 88% retention rate through a molt compared with 55% for brands and 16% for elbow tags. By June 1968 approximately 98% and 77% of the November release of back-tagged ...

Movements, growth and survival of marked and tagged lobsters liberated in Egmont Bay, Prince Edward Island : Wilder, D. G., 1963. J. Fish. Res. Bd., Canad., 20 (2): 305–318

The Scaphopoda are marine infaunal carnivores that feed on foraminiferans and other microorganisms selected and manipulated by their unique feeding tentacles or captacula. Their tusk-like shell is open at both ends; the burrowing foot and captacula protrude anteriorly, while respiratory currents pass through the posterior opening. Although the scaphopods comprise one of the smallest molluskan classes in terms of species diversity, they have a worldwide distribution ranging from intertidal to depths in excess of 6000 m.Despite detailed monographic work from the late nineteenth and early twentieth centuries, however, the biology of scaphopods is today among the least understood of mollusks. To some extent, this is related to a significant departure from more typical molluscan organization inferred from studies of the larger classes. For example, the mantle cavity is elongate and restricted in space, and several associated organs are lost, including the osphradium and ctenidia; the latter is associated with the loss of auricles from the scaphopod heart. There is also little record of ontogeny in the adult shell, as the older portion is periodically decollated to maintain the posterior aperture for passage of inhalant and exhalant currents. This and other constraints on scaphopod diversification are reflected in the range limits of shell shape within the class.In contrast, the “Dentalium” egg has been a model system for experimental embryology, particularly in studies of cell lineage and early morphogenesis. Later larval development and most organogenesis is nonetheless poorly known, although recent studies have considerably enhanced our knowledge in this area.Global biogeographic patterns of scaphopod diversity have been studied only preliminarily. A general decrease in diversity with depth is broken by small diversity peaks at bathyal depths. There is also evidence for a marked latitudinal diversity gradient in the world's oceans, near equatorial in the Pacific but at ∼20°N in the Atlantic.Scaphopods have a wide diversity of ecto- and endo-symbiotic associations with other organisms, including commensal bacteria and ciliates, mutualistic anemones and corals, and parasitic algae and platyhelminths. Other documented associations include predation by naticid gastropods and ratfish, and the inhabitation of empty scaphopod shells by a variety of sipunculans and hermit crabs.Phylogeny within the class is still unresolved, although significant progress has been made recently in documenting morphological variation among families, genera, and species for application in a cladistic context. The evolutionary relationships of Scaphopoda within Mollusca are farther from resolution, with every conchiferan class a proposed sister group among modern analyses. Molecular avenues should provide significant progress in scaphopod phylogenetics, as indicated by recent comparative sequence analysis and gene expression patterns. Scaphopods comprise the most recent class of mollusks to appear in the fossil record, dating at least from the Mississippian Carboniferous (362.5 My). They appear from first-order occurrence data to have a substantially documented fossil record, with several sharp extinction and radiation events evident during their comparatively short geologic history.The unresolved position of the Scaphopoda within molluscan phylogeny, and their relatively limited range of morphological disparity but substantial derivation from other conchiferans, renders the scaphopods an enigmatic group. They represent a significant evolutionary avenue within the Mollusca, but one that is poorly examined. Nonetheless, comprehensive phylogenetic analysis and documentation of diversity within this small, monophyletic, class-level taxon, well-preserved in the fossil record, is imminently tractable, and presents a singular opportunity in the study of molluscan evolution.

Estimation of Catchabilities and Population Sizes of Lobsters

Techniques of estimating population size, level of fishing, and the degree of dependence of fishing success on environmental factors are examined on the basis of tagging, catch and effort data. A new method is developed to estimate population size from catch, effort, and temperature data when the catchability varies with temperature.The methods of estimation discussed are applied to data collected from a number of lobster fisheries on Canada's Atlantic coast. Analysis confirms a relationship between the catchability of lobsters and bottom temperature. Differences in this relationship are found between areas and between tagged and untagged lobsters within areas. It is suggested that these differences are attributable to the differences in densities as well as to aggregations of lobsters and fishing. The effect of these aggregations on population size estimates is considered.Calculated average catchabilities at comparable temperatures are different for different areas. These differences are correlated with the numbers of trap hauls per day per square miles fished. It is suggested that the differences in the catchabilities might be due to interactions between units of gear not predicted by the customary relationship between catch and effort.