repeated seasonal migration by a thornback ray in the southern north sea

Hunter, Ewan; Buckley, Ainsley A.; Stewart, C. P.; Metcalfe, Julian D.

doi:10.1017/s0025315405012300

Cited by 22 publications

(17 citation statements)

References 1 publication

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“…A summary of the datasets available is given in Table 1 Table S2. For 59 animals (92%) the displacement was < 30 km suggesting that these animals tended to remain in the area (Figure 1) in agreement with previous tagging studies (Hunter et al 2005a, Chevolot et al 2006a. No correlation was found between days at liberty and displacement (Pearson Product Moment Correlation=0.0528, p=0.678, n=64) indicating that the skates were not simply in transit through the area, but instead represent part of a more localised assemblage.…”

Section: Tag Returns and Available Datasetssupporting

confidence: 91%

Two’s company, three’s a crowd: fine-scale habitat partitioning by depth among sympatric species of marine mesopredator

Humphries¹,

Simpson²,

Wearmouth³

et al. 2016

Mar. Ecol. Prog. Ser.

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A sympatric assemblage of morphologically similar predators is expected to exhibit fine-scale habitat segregation, or resource partitioning, to reduce the effects of direct competition. This principle has been well studied for predators in terrestrial ecosystems.In the marine environment, how sympatric species of large predators spatially segregate at the finescale is poorly understood because detailed movement and behavioural data is often not available across multiple species within the same timeframe. How co-occurring congeneric predators separate spatially is even less well understood.Medium sized species of skates (Genus Raja) co-occur in temperate habitats of the north-east Atlantic Ocean, share similar morphologies and have distributional ranges that overlap significantly in the western English Channel ecosystem. Here, detailed depth time series retrieved from 89 electronic data storage tags attached to four species of skate were analysed to determine preferred depth ranges.The four species were found to segregate spatially into two groups, with one group having a significantly shallower core annual depth range than the other. To our knowledge fine-scale segregation by depth has not been observed previously. Interestingly the members of each species group appeared complementary, each group comprising species having different dietary preferences and with a larger and smaller body size.Habitat partitioning in marine predators 2 An understanding of how core depth ranges differ and how these species utilise vertical habitat has potential to predict geographic ranges around the coast with important implications for how these species interact with fisheries and Marine Protected Areas.

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Section: Tag Returns and Available Datasetssupporting

confidence: 91%

Two’s company, three’s a crowd: fine-scale habitat partitioning by depth among sympatric species of marine mesopredator

Humphries¹,

Simpson²,

Wearmouth³

et al. 2016

Mar. Ecol. Prog. Ser.

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“…In particular, estimated habitat range via conventional methods is typically very small in relation to tag‐release locations, suggesting that habitat overlap (“mixing”) across species or localized stocks is minimal. Therefore, without a complete understanding of movement, the use of spatial and/or temporal closures may result in the inaccurate estimation of exploitation rates, considering that skates may cross management boundaries into areas of heightened fishing mortality (Hunter, Berry, Buckley, Stewart, & Metcalfe, ; Hunter et al., 2005a). In addition, although skates are considered benthic fishes, like other elasmobranchs, vertical ranging behaviours (as reviewed below) may make them vulnerable to fishing gears which operate at various depths within the water column and across continental shelves (Coelho, Fernandez‐Carvalho, & Santos, ).…”

Section: New Insights From Emerging Tracking Technologiesmentioning

confidence: 99%

“…Unlike conventional tags, electronic tags allow researchers to (a) track skates during their time at liberty, (b) quantify distinct, repeated habitat use patterns (e.g., geography, temperature, depth, season) between species, stocks, sex or ontogenetic units, and (c) build a mosaic of migration ecology from individual movement tracks. Recent work utilizing electronic tags has shown evidence of localized population structuring and extensive seasonal migrations between egg‐laying and feeding grounds in skates, yet these phenomena are unconfirmed and an unknown degree of overlap in geographic range exists among species and/or localized stock units (Hunter et al., 2005a; King & McFarlane, ; Templeman, ; Vargas‐Caro et al., ; Wearmouth & Sims, ).…”

Section: New Insights From Emerging Tracking Technologiesmentioning

confidence: 99%

“…However, the application of recent electronic tagging technologies (e.g., data storage tags, acoustic telemetry, pop‐up archival tags, etc.) has revealed that skates do move long distances (Farrugia, Goldman, Tribuzio, & Seitz, ; Hunter, Buckley, Stewart, & Metcalfe, 2005a, 2005b; King & McFarlane, ), and display complex movement patterns across dynamic environments (Humphries, Simpson, & Sims, ).…”

Section: Introductionmentioning

confidence: 99%

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Skating on thin ice: Identifying the need for species‐specific data and defined migration ecology of Rajidae spp.

2018

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Skates (class Chondrichthyes; subclass Elasmobranchii; order Rajiformes; family Rajidae) comprise one quarter of extant chondrichthyans, yet have received little attention in the scientific literature likely due to their relatively low economic value and difficulties in species identification. The absence of species‐specific information on catch, life history and migration of skates has often precluded the development of single‐species stock assessments and led to the use of cursory multispecies assessments, which lack the ability to track species‐specific catch and abundance trends. This has resulted in undetected local extirpations, as has been previously reported for common (Dipturus batis, Rajidae), white (Rostroraja alba, Rajidae) and long‐nose (Dipturus oxyrhinchus, Rajidae) skates in the Irish Sea. Here, we (a) use case studies to illustrate how the perception of skate population structure and stock status has historically been masked through multispecies assessment and management practices, (b) review current information on the movement of skates and identify gaps in knowledge, and (c) identify biases associated with the use of various tagging technologies, which have confounded our understanding of movement and migration ecology of skates. Considering that over 40% of extant Rajidae species are listed as “Data Deficient” by the International Union for Conservation of Nature, we illustrate a critical need to broaden the current understanding of skate life history, movement and migration ecology by providing recommendations on the further application of electronic tags and biogeochemical natural tags in movement studies and highlight the benefits that studies using these approaches have for novel management frameworks.

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“…Many elasmobranch species are highly migratory, particularly with reference to specific nursery areas, with marked seasonal movements between the North Sea and Thames estuary for R. clavata having already been observed (Hunter et al, 2005). Therefore, it may be expected that such seasonal movements would affect capture vulnerability in commercial fisheries, and hence patterns of availability to consumers.…”

Section: Resultsmentioning

confidence: 99%

DNA barcoding unveils skate (Chondrichthyes: Rajidae) species diversity in ‘ray’ products sold across Ireland and the UK

Griffiths

Miller

Egan

et al. 2013

PeerJ

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Skates are widely consumed across the globe, but many large species are subject to considerable concern regarding their conservation and management. Within Europe such issues have recently driven policy changes so that, for the first time, reports of skate landings now have to be made under species-specific names. Total allowable catches have also been established for many groups, which have been set to zero for a number of the most vulnerable species (e.g., Dipturus batis, Raja undulata and Rostoraja alba). Whilst accurate species identification has become an important issue for landings, the sale of skates is still usually made under a blanket term of “skate” or “ray”. The matter of identifying species of skate is further complicated by their morphologically conservative nature and the fact that they are commercially valued for their wings. Thus, before sale their bodies are usually discarded (i.e., “winged”) and often skinned, making morphological identification impossible. For the first time, DNA barcoding (of the mitochondrial COI gene) was applied to samples of skate wings from retail outlets across the British Isles, providing insight into which species are sold for consumption. A total of 98 wing samples were analysed, revealing that six species were sold; blonde ray (Raja brachyura), spotted ray (Raja montagui), thornback ray (Raja clavata), cuckoo ray (Leucoraja naevus) small-eyed ray (Raja microocellata) and shagreen ray (Leucoraja fullonica). Statistical testing demonstrated that there were significant differences in the species sold in the distinct retail groups which suggests complex drivers behind the patterns of sale in skates. The results also indicate that endangered species are not commonly being passed on to consumers. In addition, the practice of selling skate wings under ambiguous labels is highlighted as it makes it extremely difficult for consumers to exercise a right to avoid species of conservation concern. Interestingly, a single retailer chain labelled their wings as originating from three smaller-growing species (generally to be considered of lower conservation concern); of the six samples analysed from this company a third were mislabelled and originated from the thornback ray (a larger species that is currently undergoing population declines).

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repeated seasonal migration by a thornback ray in the southern north sea

Cited by 22 publications

References 1 publication

Two’s company, three’s a crowd: fine-scale habitat partitioning by depth among sympatric species of marine mesopredator

Two’s company, three’s a crowd: fine-scale habitat partitioning by depth among sympatric species of marine mesopredator

Skating on thin ice: Identifying the need for species‐specific data and defined migration ecology of Rajidae spp.

DNA barcoding unveils skate (Chondrichthyes: Rajidae) species diversity in ‘ray’ products sold across Ireland and the UK

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