The Azorean Loligo forbesi (Cephalopoda: Loliginidae) in captivity: transport, handling, maintenance, tagging and survival

Abstract

The population of Loligo forbesi inhabiting the Azorean Archipelago achieves the largest size ever reported for this species but also for any Loliginidae. Despite their importance as a food source for local communities, very little is known about their biology and ecology. In this paper, we describe our efforts in capturing, transporting, handling, tagging and holding wild adult L. forbesi in the laboratory. Three culture trials were conducted in the Island of Faial, Azores. Over 84 squid were captured by jigging, transported in separate containers and placed in a recirculating seawater system composed of three 3.6 m circular tanks (8000 l capacity each). Drawings and technical details about the system (filtration system, tanks, liners, illumination, flow rates, etc.) as well as water quality parameters (ammonia, nitrite, nitrate, iron, pH, salinity and temperature) are presented. By keeping squid in separate bags and providing constant water flow, no mortality occurred during transport from fishing ground to the laboratory. Mean survival time for each trial was 8 days (1503 g mean weight), 17 days (595.1 g mean weight) and 11 days (826.1 g). A small female remained alive for 44 days. In this system, mortality was faster for larger squid. Low survival time could be attributed to bad water quality management, namely high ammonia levels and high temperature variations but also restricted swimming space for larger squid (.1000 g). Pin tags proved to be the most adequate method of distinguishing between individuals. Squid were fed a variety of fish species, either fresh or defrosted. Daily feeding rates varied between 0 and 7.8% body weight (BW day 21 ). Most squid lost weight or did not grow. However, some individuals showed a positive increase in BW, varying between 0.009 and 1.4% increase in BW day 21 . Key factors to take into account for increasing laboratory survival are: (1) catching squid with jigs; (2) prevention of skin damage during transport;(3) maintenance of small individuals; (4) segregating sexes to reduce agonistic interactions; (5) providing good water quality; and (6) abundant food supply.

First description of spawning in a deep water loliginid squid,Loligo forbesi(Cephalopoda: Myopsida)

“…All squid were caught by jigging, and kept in a closed seawater system. The system consisted of three circular tanks (3.6 m ∅︀, Ø0.90 m high) painted with vertical dark stripes on the walls and with 4 cm of gravel on the bottom (for details see Gonçalves et al , 1995). The tanks were covered by a black lid to keep light at low intensities.…”

“…Squid were fed on fresh and frozen fish once or twice a day ad libitum . Each squid was tagged on the mantle following the method described by Gonçalves et al (1995). A group of three spawning events (C1, C2 and C3) was observed during that period but no mating activity was observed.…”

Simulating the indirect handline jigging effects on the European squid Loligo vulgaris in captivity

“…Experimentation with captive squid has been used to describe different life history traits of squid (O'Dor et al, 1977(O'Dor et al, , 1994Hanlon, 1978;Hanlon and Messenger, 1996), including behavioural features (Porteiro et al, 1990;Hanlon and Messenger, 1996). It is difficult to keep most squid species in captivity in good condition (Hanlon and Messenger, 1996;Gonç alves et al, 2009). Fortunately, most of the species specificities of L. vulgaris are known (Turk et al, 1986;Lipinski, 1987;Vidal et al, 2005;Villanueva, 2000).…”

“…Adults of the European squid Loligo vulgaris were caught during experimental angling sessions at sunset (day moment with a maximum angling pressure and the best efficient catch rates; unpublished data Cabanellas-Reboredo) by handline jigging because this method minimises stress and damage (Porteiro et al, 1990;O'Dor et al, 1994;Gonç alves et al, 2009). Squid were placed into a 100-l tank as soon as they were caught.…”

Movement patterns of the European squid Loligo vulgaris during the inshore spawning season

“…2A). Our fishing and handling protocols (O'Dor et al 1995, Gonçalves et al 2009) minimized the stress and damage to the squid. The squid were immediately sexed, the dorsal mantle length (DML) was measured, and the squid were gently placed on a damp cloth where they were tagged (Fig.…”