Energy expenditure during activity in the American lobster Homarus americanus: Correlations with body acceleration.

How animals manage time and expend energy has implications for survivorship. Being able to measure key metabolic costs of animals under natural conditions is therefore an important tool in behavioral ecology. One method for estimating activity-specific metabolic rate is via derived measures of acceleration, often 'overall dynamic body acceleration' (ODBA), recorded by an instrumented acceleration logger. ODBA has been shown to correlate well with rate of oxygen consumption (V˙o2) in a range of species during activity in the laboratory. This study devised a method for attaching acceleration loggers to decapod crustaceans and then correlated ODBA against concurrent respirometry readings to assess accelerometry as a proxy for activity-specific energy expenditure in a model species, the American lobster Homarus americanus. Where the instrumented animals exhibited a sufficient range of activity levels, positive linear relationships were found between V˙o2 and ODBA over 20min periods at a range of ambient temperatures (6, 13 and 20°C). Mixed effect linear models based on these data and morphometrics provided reasonably strong predictive power for estimating activity-specific V˙o2 from ODBA. These V˙o2-ODBA calibrations demonstrate the potential of accelerometry as an effective predictor of behavior-specific metabolic rate of crustaceans in the wild during periods of activity.

Temporal trends in antibody production in captive grey, harp and hooded seals to a single administration immunocontraceptive vaccine.

The temporal production of antibody to a single-administration immunocontraceptive vaccine, known to be immunocontraceptive in free-ranging female grey seals (Halichoerus grypus), was studied in captive grey seals, harp seals (Phoca groenlandica) and hooded seals (Cystophora cristata). The vaccine is based on liposome delivery of porcine zona pellucida antigens. When measured by antigen capture, the response of hooded and harp seals to the vaccine was similar to the response of grey seals. Determination of antibody production by ELISA with protein A, ELISA with rabbit anti-seal immunoglobulin sera and SDS-PAGE after affinity chromatography confirmed the similarity in response to the vaccine by grey and harp seals, but suggested lower titers in hooded seals. The vaccine produced titers in captive, juvenile grey and harp seals known to be immunocontraceptive in wild, adult grey seals.

Evidence for a long-lasting single administration contraceptive vaccine in wild grey seals.

A single-administration birth control vaccine based on liposome delivery of porcine zona pellucida antigens reduced pup production in grey seals (Halichoerus grypus) by about 90%. Anti-porcine zona pellucida titers of individual seals with two or more recaptures were variable but without a diminishing trend during the 5 year post-immunization period. Seals that produced at least one or more pups during the 2-5 year post-immunization period when the vaccine is fully effective, had an average anti-porcine zona pellucida titer of 5% of the reference serum. In contrast, the subset of seals that did not reproduce but were recaptured during the breeding season had an average titer of 31% of the reference serum. As measured by antibody titers and pup production, there were no differences in efficacy of the vaccine in 14-, 20- and 21-year-old female grey seals.

Use of electroejaculation to collect semen samples from wild seals.

Semen samples were obtained from 7 adult male gray seals (Halichoerus grypus) at a colony on Sable Island, Nova Scotia, Canada, using a portable electroejaculation system. Males were anesthetized with tiletamine-zolazepam. A probe was inserted in the rectum, and a progressive series of 10 to 15 stimulations (1 to 9 V, 25 to 750 mA) was applied. Males ejaculated after 15 to 29 minutes of stimulation and produced ejaculates with volumes of 4 to 17 ml that had vigorous, motile spermatozoa. Although trials were performed in winter conditions (0 to -15 C), simple storage methods (semen samples collected into plastic bags and placed in a warm pocket or an insulated cooler) kept spermatozoa motile for up to 4 hours after ejaculation. The procedure described here provides a means for collection of semen samples for genetic analyses and tests of reproductive competence in seals.