Spiny Lobster

Along the coast of Baja California Sur, spiny red lobster Panulirus interruptus is marketed and exported live. During the fishing season, water temperature varies from subtropical to temperate and transportation of live lobsters may exceed 24 h. This experiment simulated live lobster transport using lobsters that had been acclimated for 48 h at either 20 °C or 26 °C. Lobsters were then placed in Styrofoam containers, covered with sawdust, and remained in this condition for 3, 6, 12, or 24 h. After each treatment, lobster gills were dissected for histological analysis. There was a significant effect (p < 0.05) of temperature and emersion time on gill lamellae area, perimeter, and form factor. Gill lamellae area and form factor significantly decreased (7% and 13%) for lobster acclimated at 26 °C, while the perimeter increased (3%). After emersion for 24 h, the contact surface for respiratory exchange had significantly decreased, while the form factor increased. Based on these results, we developed an index of gill collapse to relate loss of lamellae form and respiratory function. After 24 h of emersion, 69% of the gill lamellae had collapsed at 26 °C, but at 20 °C, only 28% of the gill lamellae had collapsed. These changes had no effect on the survival of spiny red lobster, suggesting a morpho-physiological mechanism of tolerance to emersion, in which the shape and area of the gill lamellae recovers by producing mucus (mucopolysaccharides or glycosaminoglycans).

En Baja California Sur se comercializa y transporta viva la langosta roja, Panulirus interruptus. Durante la temporada de captura la temperatura del agua puede variar de condiciones semi-tropicales a templadas mientras que los tiempos de traslado al punto de venta pueden superar las 24 h. Se realizó un experimento donde se aclimataron langostas por 48 h a dos temperaturas experimentales (20 y 26°C) para después simular en el laboratorio el transporte en vivo. Las langostas fueron colocadas en hieleras de poliuretano, cubiertas con aserrín y la hielera sellada para simular tiempos de traslado de 3, 6, 12, 24 h durante los cuales las langostas permanecieron en emersión. Pasado el tiempo de emersión se sacrificaron 15 langostas por tratamiento, se disecaron las branquias y se realizaron cortes histológicos para evaluar los cambios morfológicos de las lamelas branquiales en P. interruptus. Los resultados mostraron un efecto significativo (p<0.05) de la temperatura, del tiempo de emersión, y de la interacción en el área, factor de forma y perímetro de las lamelas branquiales. El área y el factor de forma de las lamelas branquiales disminuyen significativamente (7 y 13%) a la mayor temperatura mientras que el perímetro se incrementa (3%). A las 24 h de emersión la superficie para intercambio respiratorio disminuye significativamente mientras que el factor de forma se incrementa. En base a los resultados se propone el índice de colapsamiento (IC) como un indicador de pérdida en la forma y el funcionamiento de la lamela branquial. El 69% de las lamelas branquiales se colapsaron a 26°C a las 24 h de emersión mientras a 20°C solamente el 28% de las lamelas branquiales se colapsaron. Estos cambios no repercuten en la sobrevivencia de P. interruptus lo que sugieren un mecanismo morfo-fisiológico de tolerancia a la emersión que le permite recuperar el área y la forma de la lamela basado en la producción de mucinas (mucopolisacaridos o glicosaminoglicanos).

This 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, withhigher 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.