The Sizes, Growth and Reproduction of Arrow Worms (Chaetognatha) in Light of the Gill-Oxygen Limitation Theory (GOLT)

The Chaetognatha are a marine invertebrate phylum including 132 extant, carnivorous species in nine families and two orders, but with unclear protostomian affinities in the animal kingdom. We document the gradual recognition of the distinctiveness of chaetognaths by early taxonomists, with some emphasis on the often-overlooked studies by Chinese marine biologists. The carnivorous arrow worms are understudied relative to their importance in the marine zooplankton, where they rank second in abundance after the herbivorous copepods. Although arrow worms lack gills or other dedicated respiratory organs, we show that the Gill-Oxygen Limitation Theory (GOLT) can be used to explain how temperature and respiration affect their growth and related life-history traits. Notably, we present a reappraisal of evidence for size–temperature relationships between and within chaetognath species, and for the relationship between their temperature-mediated oxygen demand and their growth patterns. Von Bertalanffy weight growth curves of Ferosagitta hispida (family: Sagittidae) based on earlier aquarium experiments by various authors are presented, which suggest (a) a good fit and (b) that the life span of chaetognaths is much lower than suggested by the authors of several published growth curves drawn onto length–frequency samples from the wild. In addition, we show that chaetognaths attain first maturity at a fraction of the maximum length they can attain that is similar to the corresponding fraction in fishes. Overall, we suggest that the manner in which the oxygen they require enters the body of small marine invertebrates, although often neglected, is a crucial aspect of their biology. In addition, based on our result that arrow worms conform to the GOLT, we suggest that this theory may provide the theoretical framework for the study of growth in the other water-breathing ectotherms lacking gills.

Some Biological Parameters of Yellowfin Tuna (Thunnus albacares) from the Handline Fishery in the Eastern Part of the Banda Sea

Export quality yellowfin tuna (Thunnus albacares) from the handline fishery in the Banda Sea (Ambon and Seram) is vital in supporting coastal communities. To ensure its sustainability, information on their biological parameters is essential, especially for harvest strategy purposes. A combination of port sampling and fisheries surveys were conducted from January to October 2016 to monitor the catch, effort, size (length and weight), and maturity level of yellowfin tuna. An equal catch proportion of yellowfin and bigeye tuna was found during surveys in Masohi, Seram Island. In contrast, two-thirds of the catch landed in Ambon was dominated by yellowfin tuna. The catch rate varied between 25.5-71.9 kg/day. Length of samples distributed between 65-152 cm FL (mode=104 cm FL), whereas estimated live weight ranged from 6.12-148.92 kg. Both females (W=0.000001*FL3.7190) and males (W=0.000001*FL3.7438) possessed allometric growth. The proportion of males was twice that of females (1: 0.5), where most (47%) of samples were found to be mature. The estimated total mortality (Z) is 1.04/year, with the natural mortality (M) and fishing mortality (F) is around 0.55/year and 0.49/year, respectively. The stock condition allegedly reaching its optimum level tagged by the length at first caught (Lc) was slightly higher in comparasion to length at first maturity (Lm50 ) and utilization rate (E) below 0.55/year.

LENGTH-WEIGHT RELATIONSHIP AND REPRODUCTION OF SULPHUR GOATFISH Upeneus sulphureus (Cuvier, 1829) AT PPI KALIANDA, SOUTH LAMPUNG

Sulphur goatfish (Upeneus sulphureus) is the dominant caught with a fairly high level of utilization. This research aimed to analyze aspects of growth and reproduction sulphur goatfish caught by rampus nets landed at the fishing port of PPI Kalianda. Growth aspects that were observed included the length-weight, while the reproductive aspects observed is the sex ratio, gonad maturity level, and the size of sulphur goatfish at first maturity. This research was conducted in May-July 202 with the research method used simple random sampling method. The fish samples obtained during the study were 600 individuals, the results showed that Sulphur goatfish had negative allometric growth. The equation for the long-weight relationship of sulphur goatfish is log W = -4,6 + 2,9 log L or W = 2,8x10-5L2,9. The sex ratio of sulphur goatfish in May and July were not 1: 1, while the ideal condition was achieved in June. The gonad maturity level distribution of sulphur goatfish was dominated by TKG III and IV for female, while male sulphur goatfish was dominated by TKG II and III. Size at first maturity of sulphur goatfish females was 169,1 ± 1,03mm.

Assessment of Sparus aurata (Gilthead Seabream) stock in Bardawil lagoon, southeast Mediterranean Sea

During present study period from October 2020 to April 2021, gilthead seabream Sparus aurata stock was estimated by using many assessment models to evaluate actual status on Bardawil lagoon. Length at first capture (Lc) was 17.10 and 16.70 cm for females and males respectively, but it was 16.9 cm for all individuals that corresponding age at first capture (tc= 2.49 year). Length at first recruit Lr was 10.70 and 9.70 cm for females and males, respectively, corresponding age tr= 0.77 year. The length at first maturity was Lm= 18.18 cm that corresponding age tm= 2.85 years. Virtual population analysis shows some of intensive capture on S. aurata at its early life’s. Yield per recruit and biomass per recruit tend to collapse as a result of high fishing mortalities. The current study concludes an exact overfishing pressure of S. aurata stock in Bardawil lagoon.

Population Dynamics of Bullet Tuna (Auxis rochei Risso 1881) from the Indian Ocean, West Nusa Tenggara, Indonesia

Highlight Research:The bullet tuna (Auxis rochei) was identified and analysed.The length at first maturity (Lm) of bullet tuna (Auxis rochei) was analyzedThe eligibility status of bullet tuna (Auxis rochei) has been analyzed and estimatedThe LWR curve can be used to estimate age groups of fish compared to the sigmoid curveThe CF cannot be automatically used to estimate fish worth selling AbstractThe bullet tuna (Auxis rochei), BLT or tongkol lisong (Indonesian) is a species of neritic tuna which is one of the target fish for small scale fishers. The problem of bullet tuna fisheries was that it has reached overexploitation and the immature bullet tuna are still caught. This study aimed to assess the population dynamics of the BLT and its size composition caught by small scale fishers in the Indian Ocean, West Nusa Tenggara area was carried out in Bangko-Bangko (West Lombok), Cemplung Beach (South Sumbawa) and Tanjung Luar Fishing Port (East Lombok) between July 2019 and June 2020. The data was derived from the measurement and weighing results of 1,217 BLT collected from the respective collector traders at each sampling location. The growth pattern of BLT was isometric () which meant the ideal body shape (mesomorph) and length at first maturity (FLm) was 31.11 cm. The length-weight relationship curve showed that BLT was in an immature age group (adolescent fish). Meanwhile, the composition of BLT is worth selling (Condition Factor > 1.00), fit for catch (FLc / FLm > 1.00) and worthy of maturity (FLc > FLm), respectively 99.92%, 0.82% and 0.00%. The BLT fish composition indicates that the stocks of resources and populations do not support current sustainable fisheries management.

An overview of bottom trawl selectivity in the Mediterranean Sea

In the Mediterranean Sea, where bottom trawling for demersal species is the most important fishery in terms of landings, around 75% of the assessed fish stocks are overfished. Its status as one of the world’s most heavily exploited seas and the one subject to the highest trawling pressure has become a global concern. An extensive review of bottom trawl selectivity studies was performed to assess the sustainability of this fishery in the Mediterranean; the selectivity parameters were collected from 93 peer-reviewed publications of 10 countries, totalling 742 records and 65 species. The review highlighted that i) the catch of bottom trawls commonly employed in the Mediterranean, even complying with current regulations on codend meshes, still includes immature individuals for 64-68% of the species investigated, and individuals under the minimum conservation reference size (MCRS) for 78% of the species investigated, and that ii) the MCRS set for 59% of the species analyzed is well below their length at first maturity, and is therefore ecologically inadequate. Although square-mesh codends are slightly more selective, the models developed herein demonstrate that improving size and species selectivity would require considerably larger meshes, which may significantly reduce profitability. The urgent need to reduce the biological impacts of bottom trawling in the Mediterranean should be addressed by promoting the adoption of more ecologically sustainable fishing gears through the introduction of more selective meshes or gear modifications.

Reproductive Cycle and Size at First Maturity in Females of Brown Crab Callinectes Bellicosus (Stimpson 1859) in the Southwestern Gulf of California, Mexico

The reproductive cycle of the crustacean family Portunidae on the coast of the Pacific is not well known. Therefore, the reproductive cycle and the size at first maturity of brown crab Callinectes bellicosus and its relationship with environmental factors in the El Colorado Lagoon, Ahome, Sinaloa has been determined. A total of 360 females were collected from March 2012 to March 2013. The gonads were fixed in 10% formalin, histological cuts were made by the paraffin inclusion method and the hematoxylin and eosin staining technique. The diameter of oocytes was determined by stage. The size at first maturity was estimated by a logistic model. Females showed gametogenic activity during the entire study period. The maturity period was from March to November 2012, with two spawning peaks, in September 2012 and March 2013. Maturity was inversely influenced by temperature (r = -0.4454, P < 0.05) and no influence by salinity was observed (P > 0.05). The diameter of the oocytes showed significant differences between the development stages of the gonad (P = 0.001). The size at first maturity was 11.57 cm of carapace width for females of C. bellicosus.