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Thorny skate (Amblyraja radiata) have experienced decreasing abundance and range contraction in the Gulf of Maine (GOM) in recent decades. To better understand the extent to which population structure, environmental conditions, and movement ecology may play a role in these disruptions, 128 “mark-report” pop-up satellite tags (mrPATs) and 2195 conventional tags were deployed from 2002 to 2019. Data obtained from 84 mrPATs and 43 conventional tag recaptures [127 individuals: 55 males, 72 females; 32–104 cm total length (TL)] revealed minimum linear horizontal movements of 0.4–46.8 km in all cardinal directions over periods 22–3435 d. There was no relationship between days at liberty, TL, sex, depth, reporting season, or tag type and minimum linear displacement, and no broad seasonal movements were evident. Skates were observed at depths 27–201 m and in water temperatures 2.5–12.5°C, with fluctuations in both depth and temperature evident by season. Given their restricted movements, thorny skate may represent a single stock/population with metapopulation-like structure in the GOM. The pervasiveness of sedentary behaviour may also place the species at risk of localized depletion and climate change but also demonstrates the potential efficacy of spatial closures for promoting population recovery.

Discard mortality (DM) estimates are vitally important to fisheries management. Commercial fishery DM estimates, for example, can help calculate total fishing mortality and biologically acceptable catch limits. The winter skate, Leucoraja ocellata, is the only species within the US portion of the western North Atlantic that is targeted in the skate wing fishery. However, due primarily to fishery regulations, this species is also routinely discarded at sea when daily quotas are reached. While already examined in mobile fishing gears (i.e. bottom otter trawls), DM has not been addressed for the western North Atlantic skate species captured in the sink gillnet fishery, and a conservative 50% DM is used across the species of the skate complex in the management processes. Given this data gap, we estimate the DM of winter skate in sink gillnets under standard commercial fishing conditions. The study methods employed address the issue of cryptic mortality (drop out of dead skates from the gear and depredation prior to retrieval), which can bias DM estimates low for bycatch in passive gear. The degree of injury sustained during capture and handling was found to be a statistically significant predictor of mortality. Overall mean DM rates reached an asymptote within 170 h of captivity, with estimates of 11% and 17% for females and males, respectively. Based on these results, the species appears more resilient to sink gillnet capture and release than previously thought. However, cryptic fishing mortality appeared to be high for extended soak times and likely represents an important focus of future research and management actions.

Thorny skate (Amblyraja radiata) remain one of the most overfished species in the Gulf of Maine (GOM) despite being designated as a prohibited (zero-possession, mandatory release) species by the New England Fishery Management Council in 2003. To better understand the extent to which discard mortality (DM) occurring after incidental capture in the GOM groundfish bottom trawl fishery may be impeding recovery, 75 individuals (55–94 cm total length, TL) were tagged with pop-up satellite archival transmitting (PSAT) tags and monitored for up to 28 days following capture under representative commercial trawl fishing practices. Data recovered from 61 PSAT-tagged skate were analysed with a longitudinal survival analysis to estimate DM and identify influential capture-related variables. DM rate was a function of TL, with larger skates (>70 cm; DM = 16.5%) experiencing lower mortality than smaller conspecifics (55–70 cm; DM = 24.5%). From our results, we estimate annual thorny skate DM in the GOM groundfish bottom trawl fishery to be 79.2 ± 0.2 mt, which accounts for

This study assessed the in vitro temporal changes that occur in blood pH and lactate concentrations for an elasmobranch species and a chelonian species, as well as blood gases (partial pressures of carbon dioxide [pCO2] and oxygen [pO2]) for a chelonian species, with a portable clinical point-of-care analyzer. Blood samples were collected from 10 cownose rays (Rhinoptera bonasus) and 10 red-eared sliders (Pseudemys scripta elegans), stored on ice, and serially analyzed at six time points up to 90 min postcollection. Results indicate that analysis should be conducted as soon as possible after blood collection for these species, with immediate analysis being preferred. However, if analysis must be delayed, syringes may be capped, placed on ice, and analyzed at a later time. Analysis within 90 min provided clinically acceptable results for pH and lactate in both species and for pCO2 in red-eared sliders, whereas substantial artifactual increases of pO2 were seen in red-eared sliders.