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Age and growth of bigfin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae), in Gulf of Mannar Marine Biosphere Reserve, Indian Ocean
Abstract
Statolith growth increments were analysed in the bigfin reef squid, Sepioteuthis lessoniana lineage B, for estimating the age and growth in the Gulf of Mannar Biosphere Reserve (GOM), southeast coast of India. The identification of S. lessoniana lineage B was determined by mitochondrial cytochrome c oxidase I gene sequence. The statolith increment age analysis indicated that the wild-captured squid population of S. lessoniana in the study area undergoes rapid growth. The age of S. lessoniana in males ranged from 61 (95 mm dorsal mantle length (DML)) to 220 d (390 mm DML), while it was 64 (98 mm DML) to 199 d (340 mm DML) in females. The average daily growth rate in males and females was 1.63 and 1.55 mm DML d ⁻¹ , respectively. The instantaneous growth rate varied from 0.85 (210 d) to 4.1% (110 d) for males and 0.65 (190 d) to 3.7% (110 d) for females. The age at first maturity was 114 and 120 d for males and females, respectively. Back-calculated hatching dates and the attainment of maturity in females suggested that the reproduction of S. lessoniana is year-round, with two distinct spawning peaks during July–August and February months; accordingly, the hatching dates were spread throughout the year, with the presence of two cohorts. Based on the statolith data, it can be concluded that S. lessoniana lineage B in the GOM has a potential lifespan of up to 7 months. This finding contradicts the previous growth estimates based on length-frequency data, which underestimated the true growth potential of this species.
The purpose of this research is to investigate the creation and properties of a composite material that is based on polyester and reinforced with pineapple fibers and silane-treated chitin that was obtained from the endoskeleton of an Indian squid. The curing hardener was cobalt naphthenate, and the accelerator was methyl-ethyl-ketone peroxide. The chitin extraction process involved washing, drying, and grinding the fish pen into a powder. The silane treatment of chitin was performed, which involves the hydrolysis of a silane coupling agent in an aqueous solution of ethanol and water at a 2 wt% concentration. Composite specimens were fabricated using the hand layup technique. Among the various composites, specimen PC3, containing 2.0% chitin, exhibited superior mechanical, physical, and durability properties. PC3 showed the highest tensile strength of 151.8 MPa and a tensile modulus of 5.37 GPa. It also demonstrated excellent flexural strength of 192.5 MPa and a flexural modulus of 6.33 GPa. The compression strength of PC3 was recorded at 174.9 MPa. The izod impact toughness reached 5.3 kJ/m², and the hardness was measured at 89.1 Shore-D. Wear resistance tests indicated a wear rate of 0.0024 mm³/Nm. The flammability test showed a limiting oxygen index (LOI) of 28.2%, indicating good flame resistance. For fatigue properties, PC3 demonstrated the highest endurance, with fatigue life counts of 39,741, 36,746, and 33,412 cycles at 25, 50, and 75% of UTS, respectively. Water absorption tests showed a water uptake of 1.2% after 24 h of immersion. The silane treatment of chitin enhances the chemical interaction between the fiber and the polymeric matrix by creating a Si–O–Si linkage, which improves surface hydrophobicity and compatibility with organic molecules. This treatment facilitates better bonding within the composite material, leading to enhanced mechanical and durability properties. SEM analysis revealed enhanced adhesion between the fibers and chitin fillers, leading to improved load transfer efficiency and reduced fiber pull-out. The morphology and distribution of chitin particles within the matrix further highlighted their role in reinforcing the composite, contributing to the observed improvements in mechanical, physical, and durability properties. Overall, the incorporation of silane-treated chitin from Indian squid significantly enhances the performance characteristics of polyester-based composites, presenting a viable approach for advanced material applications.
The Molecular Evolutionary Genetics Analysis (MEGA) software has matured to contain a large collection of methods and tools of computational molecular evolution. Here, we describe new additions that make MEGA a more comprehensive tool for building timetrees of species, pathogens, and gene families using rapid relaxed-clock methods. Methods for estimating divergence times and confidence intervals are implemented to use probability densities for calibration constraints for node-dating and sequence sampling dates for tip-dating analyses, which will be supported by new options for tagging sequences with spatiotemporal sampling information, an expanded interactive Node Calibrations Editor, and an extended Tree Explorer to display timetrees. We have now added a Bayesian method for estimating neutral evolutionary probabilities of alleles in a species using multispecies sequence alignments and a machine learning method to test for the autocorrelation of evolutionary rates in phylogenies. The computer memory requirements for the maximum likelihood analysis are reduced significantly through reprogramming, and the graphical user interface (GUI) has been made more responsive and interactive for very big datasets. These enhancements will improve the user experience, quality of results, and the pace of biological discovery. Natively compiled GUI and command-line versions of MEGA11 are available for Microsoft Windows, Linux, and macOS from www.megasoftware.net.
Sepioteuthis lessoniana is a widely distributed neritic squid in the Indo-Pacific Ocean. It is an important species in fisheries, but species management is difficult because of inadequate information regarding its life history. The daily growth and δ¹⁸O values from the core to the edge of statoliths of S. lessoniana collected in northern Taiwan were analyzed to predict the experienced temperature history along with ontogenetic stages. The probability of occurrence in a given area at each life stage in three seasonal groups was determined using salinity values, deduced and measured temperatures, and the known ecology of S. lessoniana. The results showed that ontogenetic variation in the statolith δ¹⁸O values in S. lessoniana reflected the seasonal temperature fluctuation observed in Taiwanese waters, which indicated the reliability of the prediction method. Complex and diverse distribution and movement patterns were observed in the three seasonal groups. The results also indicated the importance of the waters near the coast of northeastern Taiwan as a spawning ground. Based on a model prediction, the distribution of S. lessoniana is likely associated with water temperature and current. A potential migration route from the Penghu Islands to northeastern Taiwan suggests a high level of population connectivity in S. lessoniana in Taiwan. This study provides information on the spatial and vertical distribution of S. lessoniana at various ontogenetic stages, which is essential for resource management and conservation of this commercial species.
A recent revival in using cephalopods as experimental animals has rekindled interest in their biology and life cycles, information with direct applications also in the rapidly growing ornamental aquarium species trade and in commercial aquaculture production for human consumption. Cephalopods have high rates of growth and food conversion, which for aquaculture translates into short culture cycles, high ratios of production to biomass and high cost-effectiveness. However, at present, only small-scale culture is possible and only for a few species: the cuttlefish Sepia officinalis, the loliginid squid Sepioteuthis lessoniana and the octopuses Octopus maya and O. vulgaris. These four species are the focus of this chapter, the aims of which are as follows: (1) to provide an overview of the culture requirements of cephalopods, (2) to highlight the physical and nutritional requirements at each phase of the life cycle regarded as essential for successful full-scale culture and (3) to identify current limitations and the topics on which further research is required. Knowledge of cephalopod culture methods is advanced, but commercialization is still constrained by the highly selective feeding habits of cephalopods and their requirement for large quantities of high-quality (preferably live) feed, particularly in the early stages of development. Future research should focus on problems related to the consistent production of viable numbers of juveniles, the resolution of which requires a better understanding of nutrition at all phases of the life cycle and better broodstock management, particularly regarding developments in genetic selection, control of reproduction and quality of eggs and offspring.
The relative contribution of Sepioteuthis sp. 1 and Sepioteuthis sp. 2 to oval squid fishery stocks in western Japan was examined using microsatellite DNA and partial sequences of mitochondrial cytochrome oxidase subunit I. A total of 1718 Sepioteuthis spp. individuals from 19 populations were identified to determine the proportion of each species in fishery stocks. Samples from Tanegashima and Yakushima Islands in southwestern Japan were also examined to determine depth distributions. DNA was used to refer 233 (17.3 %) individuals to Sepioteuthis sp. 1 and 1421 (82.7 %) individuals to Sepioteuthis sp. 2. Sepioteuthis sp. 1 was found on the Pacific side of mainland Japan, but was predominant in Tanegashima (77.1 %) and Yakushima Islands (100 %), suggesting its distribution was limited by the warmer waters of the Kuroshio Current. In contrast, Sepioteuthis sp. 2 was most commonly found around mainland Japan. Whereas Sepioteuthis sp.1 was caught in 10 to 53 m depth, Sepioteuthis sp. 2 was caught in 2 to 30 m depth. Differences in the spatial and bathymetric distributions of these two species might reflect differences in temperature preference, spawning depth, and migration patterns. Our results would be useful for managing the fishery stocks and spawning grounds of both species.
Loliginid squids of the Sepioteuthis lessoniana complex are widely spread in the Indo-Pacific Ocean, where they constitute a commercially important resource for neritic fisheries. Sepioteuthis lessoniana is the only Lessepsian squid migrant till now, recorded for the first time in the Mediterranean in 2002 along the Turkish Levantine coasts. Two maturing males, with mantle lengths 193 mm and 244 mm, have been recently caught near the coasts of Rhodes Island (SE Aegean), extending the species distribution northward, into Hellenic waters. Their identity was confirmed by comparison of the main body, beak characteristics and morphometric measurements with those available in the literature for this species. Suspected expansion of the Lessepsian loliginid into the Aegean Sea, due to the gradual warming of the sea, is discussed.
Age and growth of Loligo
vulgaris and L.
forbesi were studied by the examination of growth increments in 96 and 135 selected (white zone <10%) statoliths, respectively. Squid were obtained by monthly sampling from the catches of commercial trawling and hand-jigs in Galician waters (north-west Spain) between February 1991 and October 1993. Mantle length (ML) of L.
vulgaris ranged from 70 to 480 mm and varied between 70 and 685 mm in L.
forbesi. A negative allometry between statolith length and ML or body weight (BW) was found in both species. Sexual dimorphism was apparent in both species, males grew faster and longer than females. The statolith analysis suggests that growth patterns of L.
vulgaris and L.
forbesi in Galician waters are different. The exploited population of L.
vulgaris was composed of two groups: one formed by individuals hatched in winter–spring and another by specimens hatched in summer–autumn. Squid hatched in winter–spring reached larger sizes at the same age than those hatched in summer–autumn. These two groups were also observed in L.
forbesi. However, squid of this species hatched in winter–spring were smaller than those hatched in summer–autumn at the same age. Reasons for this discrepancy are discussed. The life span of L.
vulgaris was about one year whereas the life span of L.
forbesi extended to 18 months.
A total of 254 mitre squid Photololigo chinensis collected in the coastal area of Tonkin Gulf was subjected to daily increment of statolith analysis to determine the ages. The oldest individuals observed were 194 days old for specimens collected in the summer-autumn season. Size-at-age relationship was best described by power function for both individuals hatched in spring-summer and autumn-winter periods. P. chinensis exhibited sexual dimorphism in the relative growth of the mantle length: males grew faster in length compared with females while weight growth rates were similar for both sexes. Seasonal factors strongly influenced the growth of squid, and the growth rates in the warm water season was higher than those in the colder season.
The big-fin reef squid, Sepioteuthis cf. lessoniana (Lesson 1930), is an important commodity species within artisanal and near-shore fisheries in the Indian and Indo-Pacific regions. While there has been some genetic and physical evidence that supports the existence of a species complex within S. cf. lessoniana, these studies have been extremely limited in scope geographically. To clarify the extent of cryptic diversity within S. cf. lessoniana, this study examines phylogenetic relationships using mitochondrial genes (cytochrome oxidase c, 16s ribosomal RNA) and nuclear genes (rhodopsin, octopine dehydrogenase) from nearly 400 individuals sampled from throughout the Indian, Indo-Pacific, and Pacific Ocean portions of the range of this species. Phylogenetic analyses using maximum likelihood methods and Bayesian inference identified three distinct lineages with no clear geographic delineations or morphological discriminations. Phylogeographic structure analysis showed high levels of genetic connectivity in the most widespread lineage, lineage C and low levels of connectivity in lineage B. This study provides significant phylogenetic evidence for cryptic lineages within this complex and confirms that cryptic lineages of S. cf. lessoniana occur in sympatry at both small and large spatial scales. Furthermore, it suggests that two closely related co-occurring cryptic lineages have pronounced differences in population structure, implying that underlying differences in ecology and/or life history may facilitate co-occurrence. Further studies are needed to assess the range and extent of cryptic speciation throughout the distribution of this complex. This information is extremely useful as a starting point for future studies exploring the evolution of diversity within Sepioteuthis and can be used to guide fisheries management efforts.
Squids typically demonstrate considerable plasticity in individual growth rates. However, it is not known if individuals growing at different rates also differ at lower levels of organisation. We wished to determine if Sepioteuthis lessoniana individuals that were larger than predicted for their age differed in their digestive gland and mantle muscle tissue proximal composition or mantle muscle structure, compared with individuals that were smaller for their age than predicted. The residual, the difference between the observed size-at-age and that predicted by the growth equation, was used as a measure of the difference in an individual's Lifetime growth from the population average. Individual squid varied considerably in their size-at-age, with juveniles showing less variation than adults. Juveniles had greater concentrations of lipid in their muscle tissue, perhaps due to an emphasis on storing energy reserves in this critical period of their life. Differences in biochemical constituents in both the digestive gland and muscle tissue were not related to the size-at-age of individuals, despite biochemical make-up being the lowest organisational level of growth. This may be due to whole animal growth and changes in biochemical composition occurring on different time scales. There was no relationship between the size-at-age of individuals and average mantle muscle fibre size. A strong relationship, however, existed between the size of mantle muscle blocks and the size-at-age of individuals for both juvenile and adult individuals, suggesting that larger muscle blocks are related to both body size and faster individual growth rates. This study demonstrates a clear relationship between mantle muscle structure and growth and the size-at-age of S. lessoniana individuals.
Recent years have seen the emergence of extensive studies of myopsid squid growth of the family Loliginidae. This has greatly advanced our understanding of their life histories. Growth data have accumulated from both statolith-based field studies and culture work. Validation studies on loliginids continue to support that statolith increments are laid down daily. Ageing work has also revealed that short lifespans are typical, with nine of the 21 species studied having lifespans <200 days, eight species with lifespans between 200 days and about 1 year and only three species with lifespans >1 year. While growth is continuous and non-asymptotic, the marked plasticity in size-at-age has hindered the development of a general model to describe squid growth. Many loliginids are multiple spawners that continue to feed while growing and reproducing, although there has been some documented loss of conditon in mature individuals. An exception is Loligo opalescens, which has a terminal spawning strategy with a marked loss of condition and post-spawning mortality. Quantification of the cost of living and the energetics of loliginids are likely to be best achieved by combining field and culture studies on a species such as the Indo-Pacific squid Sepioteuthis lessoniana.
This article is an overview of age and growth studies of squid belonging to the suborder Oegopsina, which includes the majority (~215) of squid species inhabiting offshore waters of the continental shelves and pelagic waters of the world ocean. Three main periods in the history of age and growth studies of oegopsin squid are identified. A brief history of the different methods applied to study oegopsin age and growth is presented. The lifespan of oegopsin squid varies from almost 3 months in small pelagic tropical species to 2 years in polar and deepwater species. Generally, the lifespan of similar-sized oegopsin squid increases with latitude. Growth of the majority of oegopsin squid is best described by one of the asymptotic growth functions, but some tropical squid are characterised by non-asymptotic growth. Many aspects of growth variability are discussed, such as ontogenetic, sexual, intra-specific, geographical, inter-annual and inter-specific variations. The fast growth rates of oegopsin squid give them the advantage of passing quickly through the most vulnerable first trophic levels of the oceanic food web, enabling them to compete successfully with nektonic fishes.
Statolith and gladius were investigated for their suitability as tools for age and growth studies in the loliginid squid Loligo plei off southern Brazil. Statoliths when polished, revealed a series of concentric increments deposited around a nucleus. Consistent increment counts covered the squid's entire life-time and could be considered suitable for individual age estimation. Growth increments were observed on the dorsal surface as delimited by consecutive marks formed during low growth periods. Because early growth was masked during chitin deposition, total increment counts underestimated individual age. Gladius growth was highly correlated with somatic growth, and gladius increments could be used to reconstruct individual growth histories. Both statolith and gladius increments were deposited with the same, possibly daily, periodicity. It could be inferred that L. plei off southern Brazil might live up to around nine months of age.
A technique has been developed which simplifies the ageing of short-finned squid (II'ex illecebrosus) through microstructural examination of the statotiths. The spatial pattern of growth increments was studied with the use of light and scanning electron microscopy. Daily growth increments in statoliths were validated by employing chemical "time" markers (strontium and tetracycline) and laboratory-reared animals of known age. Increment formation continued through periods of food deprivation and minimal temperature fluctuations.
Age and size-at-maturity of Loligo vulgaris from Portuguese waters were evaluated in order to explain its complex population structure, which is strongly influenced by continuous spawning. Age was obtained by increment counting in statoliths. Maturity ogives by age group indicated that males mature one month earlier (at 277 days) than females (at 298 days). Females mature at a ML50% of 17.6 cm, while males mature at smaller sizes. The later, however, showed a high degree of complexity in the size at maturity with evidence of two size at maturity groups. In both sexes, maturity was ultimately found to be primarily dependent on size rather than age. The effect of hatching season on age-at-maturity, size-at-maturity and reproductive investment was analysed by comparing two groups of squid hatched under distinct environmental conditions, namely the temperature during the first 3 months of life, the cold cohort (CC),
hatching between December and March and the warm cohort (WC), hatching between May and September. Significant differences were found between cohorts on age-at-maturity, size-at-maturity and reproductive investment, giving indication of the environmental influences on sexual maturity. CC squid mature ca. 2 months later in life than WC squid and at a significantly larger size. The reproductive nvestment as measured by GSI was higher in the WC squid. Much of the variability in age and size-at-maturity of females in the population was due to differences between cohorts but this was not the case for males.
The present study was carried out to understand some reproductive characteristics such as spawning season, variation in maturation indices with months, fecundity, sperm count and relationships between various measurements and mantle length of tropical Sepioteuthis lessoniana from the Northern coastal waters of Sri Lanka. A total of 797 specimens of S. lessoniana (404 males and 394 females) were collected from commercial catches of squid fishery and analyzed. The dorsal mantle length of male S. lessoniana ranged from 4 to 26 cm while females ranged from 3.8 to 24.3 cm. According to the morphological appearance of gonads males were categorized into immature, maturing and fully mature whereas females were categorized into immature, maturing and spawning. High occurrence of spawning stage in squids was observed in August, October, November and March. Fecundity increased exponentially with mantle length from 20 (7 cm mantle length) to 793 (26 cm mantle length). The least square linear regression analysis expressed that there are positive, significant (p<0.001) relationships for ovary weight, nidamental gland weight and oviducal gland weight with the mantle length in females and for total weight, testis weight and spermatophoric complex weight with mantle length in males. It was concluded that S. lessoniana spawns more than once, exhibits group-synchronous ovulation and intermittent terminal spawning. Peak or intense spawning of this squid in Northern coast of Sri Lanka is during March, August and October to November.
Cephalopod research in Thailand has been underway since 1978 with the goal of developing successful mass-culture techniques. Results of mass cultivation have demonstrated several favorable aquaculture characteristics of cephalopods, i.e., high growth rates, short life cycle, high fecundity, high hatching rate, and absence of true larval stages. Three species are being cultured: bigfin squid, Sepioteuthis lessoniana; spineless cuttlefish, Sepiella inermis; and pharaoh cuttlefish, Sepia pharaonis. They were listed in declining order of production and suitability for aquaculture. About 2 million cephalopod seed have been produced and released annually since 1990 to enhance natural stock. Biohistory, behavior and water quality requirements are also being studied in order to supply basic information for aquaculture. However, there are also several obstacles, particularly development of cost-effective feeds.
The life cycle of big fin squid, Sepioteuthis lessoniana, was studied in small-scale culture. Egg capsules with 2-11 embryos each were attached together in clusters; total numbers of embryo were about 1,000 per female. The incubation period was 20.3 day at 28oC. Hatchlings were planktonic. Mantle length was 0.54 cm, the weight 0.04 g. Hatchlings fed on mysids and postlarvae of penaeid shrimps. Schooling was observed from 10 days of age as squids entered the juvenile stage. Big fin squids were sexually mature after 60 days, and mating was observed after 90 days. Feed conversion efficiency was 35.81% which enabled a fast growth of 0.16 cm, or 3.47% length gain/day, and 3.82 g, or 17.22% weight gain/day. Spawning occurred at average age of 112 days. The life span was 137 days due to mortality after spawning. Average final size of the squid was 21.35 cm length and 496.88 g wet weight.
Egg cases with early-middle staged embryos of the oval squid Aka-ika, Sepioteuthis sp. 1, that were spawned on an anemometer set in the deeper layers of the coastal waters of the Ryukyu Archipelago, were collected in 2013, 2016, and 2017. However, of these only the egg cases collected in 2016 were used in this study as they had been kept in stressful conditions; packed without seawater and kept in a refrigerator at 8°C for approximately 25 h immediately after collection and were then raised under normal captive conditions in the laboratory in order to examine the effects that exposure to low temperature and oxygen levels had on later embryonic development, hatching, and hatched juveniles. We also investigated the overall feasibility of aquaculture of this species. Embryonic development proceeded followed by hatching, and the hatched juveniles survived for over 4 months. These records were compared to the survival and growth of Aka-ika Sepioteuthis juveniles not exposed to stressful conditions during their embryonic development that hatched from egg cases spawned on an artificial spawning bed set in the coastal waters of the Ryukyu Archipelago in 2016. This comparison revealed that Aka-ika Sepioteuthis embryos can develop, hatch, survive, and grow normally, even under severe stress conditions during early-middle embryonic development. This suggests that the gelatinous coat of the egg case in cephalopods might function as barrier against changeable environments during the early life phase.
Eggs of Sepioteuthis sp. 1 were collected off Tanegashima Island and incubated at 19, 23, and 26 °C. Those eggs hatched after 42, 19, and 17 days, respectively. Development took less time at higher temperatures, and at 23 °C proceeded faster than reported for S. sp. 2 cultured at 25 °C. Paralarval S. sp. 1 were cultured at 23 °C, with one surviving female and male mated at approximately 175 days after hatching. About 204 days post-hatching, the female deposited eggs on artificial seagrass and cannibalized the male. Eggs were deposited five times from 29 to 80 days after mating, after which the female died. The number of eggs in egg sheaths (0–4) was lower than counts reported for egg masses in nature (mean 9 eggs). The terminal mantle length of the mature S. sp. 1 male was 169 mm, and of the female, 173 mm. In nature, individuals at mantle lengths below 250 mm are immature, suggesting that S. sp. 1 is downsized and precocious in captivity.
The dynamics of age, growth, maturation and spawning of the Indian squid Uroteuthis duvaucelii, were determined by statolith analysis in the tropical southeastern Arabian Sea. In the samples, the smallest male (30 mm Dorsal Mantle Length) was 63 days old and the largest (350 mm DML) 170 days old. The smallest female (32 mm DML) was 62 days old and the largest female (207 mm DML) was 146 days old. The maximum life span was estimated at 6 months. Recruitment to the trawl fishery occurred approximately after two months of age. The average daily growth rates were estimated as 1.22 mm DML/day for females and 1.48 mm DML/day for males. The age at first maturity was estimated as 98 days for males and 106 days for females. Hatch dates were distributed throughout the whole year with two peaks indicating the presence of two cohorts with varying growth dynamics. The best-fitting growth models were the Gompertz growth model for females and the Linear model for the male populations based on the Akaike Information Criterion (AIC). This study suggests that fast growth and a short life span associated with a rapid population turnover may facilitate continuous recruitment to the fishery. From a conservation and management perspective, a closed fishing season during the peak spawning and hatching period (October-November) or in the consequent recruitment period may prove beneficial to U. duvaucelii population in the Arabian Sea. This study further improves our understanding of the life-cycle of multiple spawning tropical squids.
Squids support an important fishery component in the Arabian Sea. Because of this, efforts have been made during the last few decades to study the population characters of squids for an understanding of their population dynamics. Recent ageing studies interpret the growth rings in hard parts of cephalopods and it is now recognized worldwide as an accurate method. Therefore, this thesis aimed to study the age and growth of squids by using the hard part, “Statolith” of the different squid species from the Arabian Sea.
A total of 15 squid species, including five species of Myopsida squids and ten species of Oegopsida squids, were successfully aged by counting the ring formed on statoliths. Validation studies on Sepioteuthis lessoniana confirmed the “one-increment = one-day” hypothesis in squids of the tropical Indian seas. The size of the adult statoliths ranged from 606 µm in the loliginid squid Loliolus hardwickei to 1926 µm in the mesopelagic squid Octopoteuthis sp. In all the species statolith increments were visible and they were laid outside the nucleus.
Neritic myopsid squids have relatively faster growth rates when compared to oceanic oegopsid squids, except for pelagic Thysanoteuthis rhombus which had the fastest growth rate among the 15 squids studied. The statolith based age studies revealed that the lifespan of squids of the tropical Arabian Sea is short (less than 200 days) compared to temperate squids and fishes. This result proves that the currently adopted age estimation method (Length-frequency analysis) were not suitable for squids. Cohort-wise growth analysis proved that increased water temperature leads to faster growth and short lifespans. All pelagic squids have a faster growth rate and short lifespan than mesopelagic squids.
Statolith ageing techniques are confirmed as an exceptionally useful life history tool for age and growth estimation of squids from the tropical Indian Ocean. In the light of the very fast growth rate and short lifespan, squid assessment models have to be fine-tuned to account for this unique life history. Fishery researchers and managers have to take into account the very short-lived nature of squid populations and consider in-season assessment and real-time management.
This paper reports an experiment in hatching eggs and rearing young big fin squid (𝑆𝑒𝑝𝑖𝑜𝑡𝑒𝑢𝑡ℎ𝑖𝑠 𝑙𝑒𝑠𝑠𝑜𝑛𝑖𝑎𝑛𝑎 Lesson.) to the adult stage and then reproducing another generation successfully for the first time. Clusters of squid eggs were hatched in plastic baskets floating in sea water contained in cement tanks which were continuously aerated to simulate water circulation. The young squid were first fed 𝑀𝑒𝑠𝑜𝑝𝑜𝑑𝑜𝑝𝑠𝑖𝑠 sp. and 𝐴𝑐𝑒𝑡𝑒𝑠 spp. and later were fed small 𝑃𝑒𝑛𝑎𝑒𝑢𝑠 spp. and fin-fish meat as the squid age and size increased.
From the morphological point of view, the young squid developed to the adult stage within 60 days after hatching. The hatching rate of fertilized eggs was approximately 98%. The highest survival rate of squids at 30 and 60 days was approximately 54.29% and 18.86%, while the lowest survival rate was 10.77% and 5.43% respectively. The mantle length, total length and weight at 60 days were averaged 4.4 cm, 9.2 cm. and 18.5 gm. respectively. Growth and behavior was also recorded.
Age and growth of the little Indian squid Loliolus hardwickei (Gray, 1849) were studied using samples collected in the coastal waters of Arabian Sea. Statolith increment counts demonstrated that L. hardwickei has a fast growth rate (dorsal mantle length: 0.31–0.73 mm day ⁻¹ in females and 0.27–0.56 mm day ⁻¹ in males) and a short lifespan of less than 6 months. Females are the larger sex and their daily growth rates were higher than in males. The oldest male and female were 110 and 130 days old; the youngest mature female and male were 62 and 52 days old respectively. The oviducal fecundity ranged from 104–480 eggs, mean = 360 eggs (14–23 eggs g ⁻¹ body weight).
To determine the age and growth of Uroteuthis chinensis and U. edulis, growth increments of the lateral dome of the statolith were used in the present study. Specimens of the two species caught in the South China Sea (SCS) and East China Sea (ECS) were used to compare the age and growth differences between sexes. In the present study, we found the two species have similar lifespans of less than 200 days. We also found that there were significant differences in the relationships between mantle length and body weight for two species and for both sexes in the same species. The back-calculated hatching date for the two species was similar, i.e. October to January for specimens caught in spring, and March to June for specimens caught in summer (U. edulis) or autumn (U. chinensis). Exponential and logistic growth curves were fitted to build the age and mantle length relationship. Both growth curves showed that U. chinensis has a larger mantle length than U. edulis at the same age. The results of the growth rates also showed that U. chinensis grows faster than U. edulis. However, there are discrepancies between previous studies and the present study on the lifespan of the two species. Also, the sample size of the present study is small especially for U. edulis. Hence, future studies should be conducted to validate the daily periodicity of growth increment in the regions of statolith (except for the lateral dome which has been validated) and the sample size should be increased for age and growth studies. Keywords: Uroteuthis chinensis, Uroteuthis edulis, Age, Hatching date, Growth
Stock identification of oval squid Sepioteuthis spp. in the coastal waters of Tanega-shima Island were examined using ten polymorphic microsatellite loci and partial nucleotide sequences of cytochrome oxidase subunit I (COI) in the mtDNA. Also, we suggested spawning depth through eggs identification collected from artificial reefs from 20-50 m in depth. Adult specimens collected from Tanega-shima Island, identified as Akaika Sepioteuthis sp. 1 based on phenotypic characters and Tokushima waters (referred as Shiroika Sepioteuthis sp. 2) were genetically differentiated in both microsatellite allele frequencies and mtDNA sequences, which supported presence of reproductive isolation inferred by isozyme analysis. Eggs and embryos at three artificial reefs from 40-50 m in depth were identified as Sepioteuthis sp. 1, except for 20 m. Preset results indicate that Sepioteuthis sp. 1 living in Tanega-shima Island utilize 40-50 m in depth as a spawning zone. The partial COI sequences used in the present study allowed inferring phylogenetic relationship among Sepioteuthis spp. generated from Indo-Pacific region and detecting co-existence of Sepioteuthis sp. 1 and sp. 2 in Vietnam and Indonesia.
In captivity hatchling mortality was very high; between 50-100% of the dead squids were missing statoliths which are needed for swimming and orientation. Growth results are compatible with the concept of a 1 yr life cycle for this species.-from Authors
The population of Sepioteuthis lessoniana in E Australian waters grows at a very fast rate. Maturity in both sexes was achieved in <100 days. -from Author
Growth, life span and spawning season of the oval squid Sepioteuthis lessoniana were studied in the outer waters adjacent to the Kii Channel, Japan. The spawning season was estimated during June to September. The von Bertalanffy's equations were applied to monthly size compositions. They were Lt=23.2[1-exp{-0.354(t+0.044)}] for female and Lt=25.7[1-exp{-0.408(t-0.063)}] for male, where Lt was mean mantle length (cm) at t months after hatching in August. These growth rates were much larger than those observed in aquaria. The life span was one year: S. lessoniana hatched out in summer and died just after spawning in next summer.
The bigfin reef squid Sepioteuthis lessoniana is a neritic squid widely distributed in the Indo-Pacific region and of interest to fisheries for its high commercial value. The age and growth of this squid has been studied along its distribution range, from Japan to Australia; however, the life-history parameters of this squid around Taiwan are unclear. In this study, growth and maturation of S. lessoniana in the waters off northern Taiwan between April 2009 and March 2010 was studied using statolith microstructure analysis. Statoliths of 142 females (88–355 mm mantle length, ML) and 129 males (85–401 mm ML) were read. The oldest female was mature at 216 days (355 mm ML), whereas the oldest male was mature at 209 days (345 mm ML). The squids hatch almost year-round, except in January and February, peaking in May and August–September. The ML-at-age data were best described by Schnute and linear functions for the females and males, respectively. The males attained a higher size-at-age than the females. Maturity ogives by age and ML class indicated that females mature later and at a larger size than males. Growth and maturation parameters of seasonal cohorts showed little difference, although squids hatching in warmer seasons tend to have a faster growth rate and higher size-at-age than those hatching in colder seasons for both sexes. The differences of life-history traits between seasonal cohorts could be inferred by progressive changes in the life-history traits of the squids hatching during transitional months, i.e. months between two peak seasons. These results provide essential life-history traits and improve our understanding of S. lessoniana populations in the waters off northern Taiwan.
Otr experiments carried out at the Ikawazu Fisheries Laboratory, Tokyo University in 1960 proved that the fry of the squid, Sepioteuthis lessoniana, could be grown on a live mysisshrimp, Neomysis japonica, in tanks with running water, and also the rearing tried in 1961 by the same method went successfully in three species of cuttlefishes, Sepia esculenta, Sepia subaculeata and Sepiella maindroni. 1) The fry of cuttlefish and squid begin to hunt almost within 24 hours after hatching, their prey then being tiny crustaceans, such as mysis and the other larvae of shrimps. The fry of these Cephalopods appear to find sufficient nutriment in only the live mysis during the period immediately after emergence from the egg until they grow a month old. At the end of this period the fry fed sufficiently grew up to be the mantle-length of about 20mm in the cuttlefishes and 30mm in the squid. The rate of survival in every one of these species was much high, amounting to more than 80 per cent of the original fry. 2) In the Sepia and Sepiella, as they grow older, living food materials could be replaced by minced fish meat or salted mysis-shrimp placed on the bottom of tank, but such replacement seemed to be difficult in the Sepioteuthis, because they hardly cared for the dead or motionless prey. 3) Among the Sepia and other species there are some differences not only in the feeding habit as mentioned above, but in the swimming activity observed in tanks. The Sepia being rather sluggish, although S. subaculeata swims slowly about near the bottom at times, usually lie on the bottom. On the other hand the Sepiella and Sepioteuthis swim about actively and in schools.
𝑆𝑒𝑝𝑖𝑜𝑡𝑒𝑢𝑡ℎ𝑖𝑠 𝑙𝑒𝑠𝑠𝑜𝑛𝑖𝑎𝑛𝑎 is a demersal neritic species that inhabits coral and rock reefs, seaweed, sea grass beds, and estuaries. Due to its wide distribution range in the Indo-Pacific region, 𝑆. 𝑙𝑒𝑠𝑠𝑜𝑛𝑖𝑎𝑛𝑎 is an economically important resource of many countries. 𝑆. 𝑙𝑒𝑠𝑠𝑜𝑛𝑖𝑎𝑛𝑎 has been successfully cultured through multiple generations since the 1960s in both open and closed seawater systems in Thailand, Japan, and the USA. The objectives of aquaculture studies are the production of human food in tropical countries and experimental animals in temperate countries. 𝑆. 𝑙𝑒𝑠𝑠𝑜𝑛𝑖𝑎𝑛𝑎 hatchlings are larger than other loliginid squids, which enables good adaptation to culture conditions and a very high growth rate through the entire life cycle. In tropical waters, individuals can grow to 500 g in less than 150 days. This rapid growth results from a high feeding rate and requires a massive supply of live feed organisms during the early phase of life. The grow-out phase begins after 𝑆. 𝑙𝑒𝑠𝑠𝑜𝑛𝑖𝑎𝑛𝑎 can accept dead feed. Further studies of artificial feed or mass production of live feed is required in order to make aquaculture of 𝑆. 𝑙𝑒𝑠𝑠𝑜𝑛𝑖𝑎𝑛𝑎 economically viable on a large scale. The method and studies of 𝑆. 𝑙𝑒𝑠𝑠𝑜𝑛𝑖𝑎𝑛𝑎 culture in tropical and temperate waters are reviewed.
The discovery thirty years ago of daily growth increments in squid statoliths and the development of statolith ageing techniques gave new insight into squid age, growth and metabolism. The techniques have shown that the majority of recent coleoid cephalopods live in the ‘fast lane’, growing rapidly and completing their life cycles in a year or less. Surprisingly, these useful approaches to the study of age and growth in squid have not gained much momentum. Only approximately an eighth of more than 300 squid species have had their basic age assessed and described. Two dozen species are subject to continuing arguments about which increments to consider as daily growth increments. This paper outlines major problems encountered during age determination of squid and suggests ways to improve the techniques and make them applicable to a wider spectrum of species.
Periodic increments within the squid statolith microstructure are now routinely used to obtain individual age estimates. Validation and culture studies have shown that statolith increments (similar to increments in larval fish otoliths) are produced daily in a number of squid species and in one sepioid. However, sample sizes for validation studies are small and there is need for further, more comprehensive validation experiments. Statolith age analysis has revealed that temperate squids can complete their life cycle in less than 2 yr while tropical species live for less than 8 mo. Obtaining individual age estimates has also facilitated the identification of cohorts by analysing hatch date distributions. Size-at-age analysis has been used for some preliminiary growth modelling, and there is a continued need for more accurate age-based squid growth models. There is now potential to use image analysis systems for increment counts and for width analysis of increments. Future studies should be aimed at obtaining age information from a wider number of species, considering how other features within the statolith microstructure, such as zones, might reflect past habitats, and determining how statolith length or weight measurements might be related to past growth histories.
Allozyme electrophoresis was used to investigate the taxonomic status of northern calamary Sepioteuthis lessoniana (Lesson 1830) from two sites in Shark Bay, Western Australia. Of the 40 squid examined at 38 presumptive loci, four individuals from the oceanic site were clearly differentiated from the rest by fixed allefic differences at four loci (Acp, Got2, Idh2, and PepD) and near-fixed differences at another three (Est, Ocdh, and 6Pgd). The genetic distances between these two groups of individuals (13% Fixed Differences and Nei, D (1978) = 0.178) were roughly twofold greater than those between the two cryptic taxa in the southern calamary S. australis, but are considerably smaller than those between the northum and southern calamary. The most likely explanation for these data is that S. lessoniana comprises two "cryptic" biological species in this region. Further studies are needed to delineate the total number of species found throughout Australasia for this important loliginid squid. (c) 2005 International Council for the Exploration ofthe Sea. Published by Elsevier Ltd. All rights reserved.
Age and growth were estimated on two brood stocks of a loliginid squid, Photololigo edulis (Hoyle), by examining growth increments within the statoliths from 773 specimens. Samples were collected from the northwestern coast of Kyushu, Japan, and the southwestern coast of the Sea of Japan between January 1983 and June 1984. Length and age data were fitted to logistic growth curves for each sex and brood, under the assumption that increments formed daily. Relationships between age and mantle length and the modelled growth curves showed that: the posthatch life span may be < 1 yr; growth rates vary considerably between individuals, especially in the second half of life; the average growth rate of the male was higher than that of the female in the warm-season brood, but almost the same in the cold-season brood. Because of the wide variation in the individual growth rate, it was presumed that warm- and cold-season broods were not genetically discrete populations.
The study of cephalopod populations currently lacks the means to define populations adequately and to resolve basic systematic confusions. Quantitative data are usually only available from indirect sources such as commercial fisheries and from estimates of consumption by higher predators. Despite these methodological difficulties it is clear that cephalopods comprise a major component of biomass globally, throughout all fully marine habitats. Life-cycle characteristics common to the coleoids - early and/or semelparous breeding, rapid growth, short lifespan, little overlap of generations, vulnerability to predation and environmental variables - result in wide inter-annual fluctuations in abundance. Most of the pelagic forms also undertake large- or meso-scale migrations which, coupled to shifting patterns of oceanographic variables, contribute to the unpredictability of distribution and density associated with many cephalopod species. Temporal and spatial patterns of breeding, seasonality, growth, recruitment and mortality are clearly evident in most of the better-studied species. But exceptions to pattern (e.g. variable growth rates, extended breeding, complex recruitment) also seem to be important intrinsic characteristics. Levels of genetic variation in cephalopods are relatively low, and their population dynamics appear to be influenced principally by phenotypic plasticity in response to environmental variability. In such universally short-lived species the maintenance of this diversity balances the risks of mortality factors combining at any one time to cause periodic local extinction. The extent and scale of the interactions between cephalopod populations and other trophic levels suggests that major ecological perturbations such as environmental shifts, or imposed effects such as commercial fishing, whether directed at cephalopods or other species, are likely to have an impact on their populations. As short-lived species with high turnover of generations, plastic growth and reproductive characteristics, high mobility and catholic predatory habits, they are always poised to respond to changed balances in their environment. Studies on cephalopod populations have expanded considerably in numbers and scope in the last 25 years, driven by increased interest in and recognition of their roles in the marine ecology, as well as their increasing value as globally exploited resources. Despite these recent advances, the information and concepts arising from their study is only slowly entering mainstream biological thought and becoming accommodated in broad-scale models of the marine ecosystem.
Over 2000 individuals of Lolliguncula brevis were collected from 1975 to 1979 in the northern Gulf of Mexico off the Texas coast; their growth and reproductive biology were analyzed by traditional fisheries methods (ELEFAN analysis of the length-frequency data). From 1994 to 1996, 112 squid were captured in Galveston Bay, near Galveston Island, Texas, and their age and growth determined by statolith increment analysis. The results were strikingly different between the two approaches. Length-frequency analysis of growth overestimated life span by a factor of three to seven times. Statolith increment counts, verified by laboratory growth validation experiments, indicate that this species is very short-lived, in the order of 100-200 days depending on temperature. A slight increase in temperature during the early stage of development can greatly shorten the life span. This study provides evidence that increased temperature during a squid's early growth period could markedly accelerate growth. Mature individuals occurred throughout the year, although there were many more mature males collected than females. Gonad growth and maturation in L. brevis appear to be associated more with size than with individual age. There is now compelling evidence that length-frequency analysis should be abandoned as a technique for determining squid growth.
Eggs of Sepia esculenta, S. subaculeata, Sepiella maindroni, Sepioteuthis lessoniana, and Euprymna berryi were hatched in concrete cisterns. The fry were fed live and dead invertebrates and fishes and were raised to near-adult sizes. Live mysids appeared to be a favored food. Details of the culture methods are given and observations noted on behavior and growth of each species.
The statoliths of 33 Sepioteuthis lessoniana from Bolinao, north-western Luzon, Philippines, were examined microscopically for growth increments. The daily nature of the increments was verified for captive specimens (<6 cm) kept in a tank containing Alizarin solution and fed with shrimps previously soaked in Alizarin solution. The ages ranged from 30–40 days in juveniles (19–33 mm dorsal mantle length DML) to 62–132 days in adults (62–315 mm DML). The growth rates estimated (0.5 mm·day−1 in adults) were much higher than those estimated by length-frequency analysis, but compatible with published estimates based on the statoliths of specimens sampled in Australia and Japan. The discrepancy between the results of length-frequency analysis and statolith ageing is attributed, at least in part, to underestimation of the age of older squid.
Three consecutive generations of the oval squid, Sepioteuthis lessoniana, were cultured between October 2000 and May 2002 to investigate the life history of this species. Starting with the parental generation (wild-caught sub-adult squid from Tokushima Prefecture, Japan), we successfully obtained first and second generations. Life span and maturation of cultured oval squid and wild oval squid caught from the same habitat during April 2001 through to March 2002 were compared. Captive squid matured earlier and had a shorter life span (189–247 days) than the wild-caught squid (approximately one year) but reached an equivalent final body size. More ova were found in the oviducts of cultured females than in the oviducts of wild-caught females. Ultimately, collapse of the culture population was mainly due to the low rate of embryonic development of spawned ova, which might have resulted from the abnormal arrangement of ova in egg cases produced by later generations of females.
INTRODUCTION
Growth laminations were first noted in squid statoliths by Clarke (1966), who suggested they might be useful for age determination. Spratt (1978) presented a detailed age analysis of Loligo opalescens Berry, 1911, arguing that some rings in the cephalopod statolith were deposited daily, as are fish otoliths (Panella, 1971). Growth rings in Illex illecebrosus (Lesueur, 1921) statoliths were illustrated by Lipinski (1978) with similar interpretation to that of Spratt ( op. cit. ). Several further attempts have been made to validate and/or to discuss age determination from statoliths (Hurley, Drew & Radtke, 1979; Hurley et al. 1983; Wiborg, 1979; Hurley & Beck, 1980; Kristensen, 1980; Lipinski, 1980, 1981; Rosenberg, Wiborg & Bech, 1981; Martins, 1982; Radtke, 1983; Dawe et al. 1984), and several other attempts are in preparation (R. J. Hanlon, G. V. Hurley, M. R. Clarke & R. L. Radtke, personal communications).
Samples of two loliginid squids Alloteuthis africana and A. subulata were collected from the continental shelf off the west Sahara in August-September 1987. Statoliths were taken from 124 specimens and processed using statolith ageing techniques. Statoliths of both species were very similar in shape. In the ground statolith, growth increments were examined and grouped into four growth zones distinguished mainly by the width of the increments. Age of adult mature males of both species did not exceed eight months, that of females six months. Alloteuthis africana grew faster than A. subulata in weight and, particularly, in length. At age 180 d the mantle of A. africana was twice as long and the body weight 1·2–1·5 times as large. Both species matured over a wide range of sizes and ages (from 120 to 180 d). The life span of A. africana and A. subulata hatching between January and May on the west Saharan shelf is about six months, much shorter than that of A. subulata in its northern temperate range.
Terms, dimensions and ratios for statolith description are defined. The form of the calcareousstatoliths in the Teuthoidea, Sepiodea and Octopoda is described by reference to Loligo forbesi, Sepia officinalis and Eledone cirrosa. While statoliths change in form and size during the growth of a cephalopod, the adult form is often characteristic for a species, despite some variation. Description of statoliths is important in studies of the fossil remains of cephalopods lacking calcareous shells, and will probably become important in the taxonomy of living species, in food analysis of cephalopod predators and in the study of deep sea deposits.