Seasonal migration of the starry smooth-hound shark Mustelus asterias as revealed from tag-recapture data of an angler-led tagging programme

The primary aim of this long-term angler-led tagging programme was to gain information about seasonal changes in distribution of the starry smooth-hound shark Mustelus asterias, along the Dutch coast for management and conservation purposes. Between 2011 and 2014, M. asterias comprised 92·6% (n = 2418) of the total elasmobranch catch (n = 2612) by the licenced group of taggers within the Dutch Delta of which 2244 M. asterias were fin-tagged with plastic rototags. Sex and total length (LT ) composition inside the eastern tidal basin (Oosterschelde) were significantly different, i.e. more females and larger individuals, than outside indicating a pupping ground, which was confirmed by the capture of 30 newborn pups (≤32 cm). The distribution pattern of reported recaptured M. asterias (return-rate 3·6%, n = 80) showed a circannual migration between summering in the southern North Sea and wintering in the English Channel and the Bay of Biscay, and suggests that M. asterias is philopatric. The Dutch angling season for M. asterias runs from approximately mid-May to mid-October when the water temperature is above 13° C. Recaptures of eight mature females, but no males in the Bay of Biscay, indicate partial spatial segregation by sex, where mature females migrate over larger distances than immature females and males. These observations, with the absence of recaptures in other known summering areas (i.e. the Irish Sea and Bristol Channel), suggest that the southern North Sea is used by a separate population. Implications for management and recommendations to improve and expand the study approach are discussed.

Biological data from a data-deficient shark: the Arabian smoothhound Mustelus mosis (Carcharhiniformes: Triakidae)

The present study provides information on length distribution, reproductive biology and diet of Mustelus mosis based on individuals caught in waters off the eastern Arabian Peninsula. Although ageing of vertebral centra was attempted, band pairs were of low clarity and counts could not be confidently assigned.

Reproductive biology of the starry smooth-hound shark Mustelus asterias: geographic variation and implications for sustainable exploitation

Examination of the reproductive biology of Mustelus asterias in the north-east Atlantic Ocean highlighted apparent geographical variation in maturity, fecundity and ovarian cycle between Atlantic and Mediterranean populations. The stretch total length (L(ST) ) and age at 50% maturity for Atlantic males and females were estimated at 78 cm L(ST) and 4-5 years and 87 cm L(ST) and 6 years, respectively. Size at maturity of females was considerably smaller than in Mediterranean specimens (96 cm L(ST) ). Ovarian fecundity ranged from eight to 27 oocytes and uterine fecundity from six to 18 embryos. The gestation period was c. 12 months, followed by a resting period of c. 12 months, resulting in a biennial cycle. Females stored sperm in the oviducal gland and, unlike Mediterranean specimens, no uterine compartments were observed in Atlantic specimens. This study reveals the existence of strong, possibly adaptive, divergence in life-history traits in an elasmobranch, whose northern populations may be more susceptible to overexploitation than previously believed.

Hip disarticulation using the lateral approach: a new technique

A new approach to hip disarticulation is described. This technique uses a laterally based racquet incision. The advantage of this incision is that it uses a lateral approach to the hip, which is familiar to orthopaedic surgeons. This approach is combined with a circumferential incision to facilitate exposure of neurovascular structures. By basing the incision on the lateral approach to the hip, dissection of large blood vessels is minimized, which helps to decrease operative blood loss. Viability of the soft tissue flaps is excellent, with only two minor wound complications occurring. Phantom limb pain was minimal, and no patient required pain medication beyond the 3-month postoperative routine. The three patients who chose to use prostheses had no difficulty from the incisions. The clinical significance of this study is to enable orthopaedic surgeons to do hip disarticulation using the familiar anatomy of the lateral approach to the hip.

Compression arthrodesis of the ankle by triangular external fixation: biomechanical and clinical evaluation

This article describes a technique of ankle arthrodesis using a triangular external fixation frame and presents the results of biomechanical analysis and clinical experience with the frame. Clinical evaluation of 23 ankle arthrodeses performed using a triangular external fixation frame yielded a 91.3% fusion rate at an average of 11 weeks postfusion. The triangular frame was 79% stiffer than a compression-only external frame in torsion and 39% stiffer in anteroposterior bending. This high rate of fusion is attributed to the elimination of micromotion at the fusion site because of the increased rigidity of the triangular external compression frame.