Jaruwat Nabhitabhata

World squid fisheries

Abstract Some 290 species of squids comprise the order Teuthida that belongs to the molluscan Class Cephalopoda. Of these, about 30–40 squid species have substantial commercial importance around the world. Squid fisheries make a rather small contribution to world landings from capture fisheries relative to that of fish, but the proportion has increased steadily over the last decade, with some signs of recent leveling off. The present overview describes all substantial squid fisheries around the globe. The main ecological and biological features of exploited stocks, and key aspects of fisheries management are presented for each commercial species of squid worldwide. The history and fishing methods used in squid fisheries are also described. Special attention has been paid to interactions between squid fisheries and marine ecosystems including the effects of fishing gear, the role of squid in ecosystem change induced by overfishing on groundfish, and ecosystem-based fishery management.

Current Status and Future Challenges in Cephalopod Culture

This chapter presents an overall perspective on the current status of cephalopod culture, its bottlenecks and future challenges. It focuses on the species that have received more research effort and consequently accumulated more sci- entific literature during the present century, namely Sepia officinalis, Sepioteuthis lessoniana, Octopus maya and Octopus vulgaris. Knowledge regarding physiology, metabolism and nutrition of different species is still lacking. Two main challenges are identified: the development of a sustainable artificial diet and the control of reproduction. Understanding cephalopod physiology and nutrition will probably be the biggest challenge in developing the large-scale culture of this group of molluscs

Early Mode of Life and Hatchling Size in Cephalopod Molluscs: Influence on the Species Distributional Ranges

Cephalopods (nautiluses, cuttlefishes, squids and octopuses) exhibit direct development and display two major developmental modes: planktonic and benthic. Planktonic hatchlings are small and go through some degree of morphological changes during the planktonic phase, which can last from days to months, with ocean currents enhancing their dispersal capacity. Benthic hatchlings are usually large, miniature-like adults and have comparatively reduced dispersal potential. We examined the relationship between early developmental mode, hatchling size and species latitudinal distribution range of 110 species hatched in the laboratory, which represent 13% of the total number of live cephalopod species described to date. Results showed that species with planktonic hatchlings reach broader distributional ranges in comparison with species with benthic hatchlings. In addition, squids and octopods follow an inverse relationship between hatchling size and species latitudinal distribution. In both groups, species with smaller hatchlings have broader latitudinal distribution ranges. Thus, squid and octopod species with larger hatchlings have latitudinal distributions of comparatively minor extension. This pattern also emerges when all species are grouped by genus (n = 41), but was not detected for cuttlefishes, a group composed mainly of species with large and benthic hatchlings. However, when hatchling size was compared to adult size, it was observed that the smaller the hatchlings, the broader the latitudinal distributional range of the species for cuttlefishes, squids and octopuses. This was also valid for all cephalopod species with benthic hatchlings pooled together. Hatchling size and associated developmental mode and dispersal potential seem to be main influential factors in determining the distributional range of cephalopods.

Analysis of neurotransmitter distribution in brain development of benthic and pelagic octopod cephalopods

The database on neurotransmitter distribution during central nervous system development of cephalopod mollusks is still scarce. We describe the ontogeny of serotonergic (5‐HT‐ir) and FMRFamide‐like immunoreactive (Fa‐lir) neurons in the central nervous system of the benthic Octopus vulgaris and Fa‐lir distribution in the pelagic Argonauta hians. Comparing our data to previous studies, we aim at revealing shared immunochemical domains among coleoid cephalopods, i.e., all cephalopods except nautiluses. During development of O. vulgaris, 5‐HT‐ir and Fa‐lir elements occur relatively late, namely during stage XII, when the brain neuropils are already highly differentiated. In stage XII‐XX individuals, Fa‐lir cell somata are located in the middle and posterior subesophageal mass and in the optic, posterior basal, and superior buccal lobes. 5‐HT is predominately expressed in cell somata of the superior buccal, anterior basal, and optic lobes, as well as in the subesophageal mass. The overall population of Fa‐lir neurons is larger than the one expressing 5‐HT. Fa‐lir elements are distributed throughout homologous brain areas of A. hians and O. vulgaris. We identified neuronal subsets with similar cell number and immunochemical phenotype in coleoids. These are located in corresponding brain regions of developmental stages and adults of O. vulgaris, A. hians, and the decapod squid Idiosepius notoides. O. vulgaris and I. notoides exhibit numerous 5‐HT‐ir cell somata in the superior buccal lobes but none or very few in the inferior buccal lobes. The latter have previously been homologized to the gastropod buccal ganglia, which also lack 5‐HT‐ir cell somata in euthyneuran gastropods. Among coleoids, 5‐HT‐ir neuronal subsets, which are located ventrally to the lateral anterior basal lobes and in the anterior middle subesophageal mass, are candidates for homologous subsets. Contrary to I. notoides, octopods exhibit Fa‐lir cell somata ventrally to the brachial lobes and 5‐HT‐ir cell somata close to the stellate ganglia. J. Morphol., 2012.

Reproductive behaviour and cross-mating of two closely related pygmy squids Idiosepius biserialis and Idiosepius thailandicus (Cephalopoda: Idiosepiidae)

Idiosepius biserialis and Idiosepius thailandicus have been previously described as separate species although the difference in morphological characters is only the arrangement of pegs in tentacular-club suckers. The former species inhabits sea grass beds in the Andaman Sea of Thailand. The latter species inhabits mangroves in the eastern Gulf of Thailand. The present study of reproductive behaviour, mating, and spawning of the two species in captivity demonstrated that they are closely related. Copulation was performed using tentacles by the male for fixation of spermatophores at the buccal region of the female. Behavioural patterns were distinguished based on the hovering and adhering positions of each sex. Cross-mating between two species was initiated and observed, yielding fertilized eggs which developed to the organogenesis stage. Reproductive behaviour of crossed pairs was similar to those of individual species. This study revealed that the two ‘species’ are not reproductively isolated.

Morphometry and morphological phylogeny of Sepia pharaonis Ehrenberg, 1831 complex in Thai waters

Three hundred and fifty-eight specimens of pharaoh cuttlefish, Sepia pharaonis, Ehrenberg, 1831 were collected from 30 localities in Thai waters, Gulf of Thailand (Pacific Ocean) and the Andaman Sea (Indian Ocean). Specimens were grouped according to sex, habitats and four categorised types of colour patterns on the dorsal mantle based on the number of stripes on the middle and lateral parts. Morphometry of 70 characters from five character sets of external, cuttlebone, digestive system, reproductive system and hectocotylus morphology were compared. The male and female cuttlefish were significantly different in 38 characters. Four types of males and females were significantly different in 29 and 19 characters. Overall, differences in colour patterns were more prominent in males than in females. Phylogenetic analyses of seven high-weighted characters revealed four likely clades of populations, corresponding to four types of colour patterns on the dorsal mantle.

Corophiine amphipods of the genera Chelicorophium and Paracorophium from the lower Gulf of Thailand (Crustacea, Amphipoda, Corophiidae, Corophiinae).

Abstract Two species of corophiine amphipods from Songkhla Lake, in the lower Gulf of Thailand, are described and illustrated. Chelicorophium madrasensis (Nayar, 1950), found in the mangrove forest, has not previously been observed in Thai waters. Paracorophium angsupanichae sp. n. is characterized by its chelate male gnathopod 2, obtuse palm with subrectangular distomedial elevation, and urosomites 1-3 free. This is the first record of the genus Chelicorophium and Paracorophium in Thai waters. All specimens are deposited in the Princess Maha Chakri Sirindhorn Natural History Museum, Prince of Songkla University, Thailand and the Museum für Naturkunde, Berlin.

A new species of Coleusia Galil, 2006 (Decapoda: Brachyura: Leucosiidae) from southern Asia.

A new species of leucosiid crab of the genus Coleusia Galil, 2006, is described from South and Southeast Asia. Coleusia huilianae n. sp. is distinguished from the superficially similar C. urania (Herbst, 1801) in the shape of the apical process of the first male gonopod which is digitate and curved laterally in the former (beak-like and curved interiorly in the latter); possessing smaller and sparser granulation on the posterior and lower margin of the cheliped and ambulatory meri; and the granulation is entirely missing from the lower external surface of the palm.

Aquaculture to Restocking

Restocking of cephalopods originated from the awareness of the depletion of natural resources and a need for conservation from stakeholders, public and private sectors. The concept of cephalopod restocking activities is to produce the cephalopod seeds and then release them back into the habitat where the species occur. The process of seed production comprises the collection of broodstocks from the wild, incubation of egg masses, post-hatching management and releasing the seeds at selected locations. The aquaculture methodology that enhances the hatching rate of the eggs and survival rate of the hatchling must produce high yields for the success of restocking. The neritic species, particularly Sepioteuthis lessoniana, Sepia spp. and Octopus vulgaris have been one key focus for restocking due to its success in previous studies on aquaculture as well as their importance to fisheries. The success of aquaculture restocking, supported by the public sector, has been outstanding in Japan and Thailand with a long historical background. Millions of cephalopod seeds were annually released during the peak activities. Although the biological significance of restocking activities to natural stocks requires further research and evaluation, the activities are considered to have produced a significant social success.

Euprymna hyllebergi and Euprymna tasmanica

Bobtail squids of the genus Euprymna are small in size with a benthic habit. Such small size results in their insignificance in fisheries and aquaculture focused for human consumption. The unique ability of the voluntary adhesion system and symbiotic bacteria used for bioluminescence is now a primary research focus with potential industrial and biomedical applications. Their small size is well suited for the home aquarium with small volume. Culture of this cephalopod group can therefore serve both research and recreational purposes. Aquaculture in the laboratory provides valuable information for culture methodology that is utilized throughout the entire life cycle of several consecutive generations. This small size and benthic habit of Euprymna are advantageous for small-scale closed or open seawater culture systems. Major trends for culturing Euprymna are similar to other cephalopod groups, particularly benthic octopus that also produce planktonic hatchlings. Reduction of the cost of production is necessary for future large-scale production, with novel protocols for live feed requirements of planktonic young in the nursing phase.