Marine and Fishery Sciences (MAFIS)

Impact of ports construction activities on structure, composition and diversity of fish population: case study of Tema, Ghana

Mon, 11 Dec 2023 00:00:00 +0000

Ports offer economic progress to many coastal developing countries. In view of the economic importance, the rising demand for maritime benefits requires the expansion of existing ports. However, marine ecosystems may become vulnerable to negative impact from the construction of these maritime structures. Therefore, the aim of the study was to establish the impact of Tema port expansion on the diversity and population structure of fish species. Data were collected quarterly from June 2018 to November 2021 through trawling fishing activities off the coast of Greater Accra, Ghana, and subsequently analysed using Primer 6 software. Sampling locations along the coast of Greater Accra included Vernon Bank (VNB), Disposal area (DSA) and Offshore Sakumono (OSK). The increased and reduced number of species at VNB and DSA, respectively, could be alluded to dredging and disposal of dredged spoils. Diversity indices at OSK site was higher than those observed in disturbed areas due to the absence of impact in this control area. Thus, it is recommended to conduct further studies on the assemblage of invasive species that migrated to the VNB during dredging activities, since these species can have severe economic impact on fishing activities of artisanal fishermen, especially at the local level.

A diagnosis of the artisanal fishery landings in the Colombian Caribbean coast by means of indicators

Camilo B. García, Luis O. Duarte — Tue, 19 Dec 2023 00:00:00 +0000

Landings of the artisanal fishery in the Colombian Caribbean from 2013 to 2021 were characterized by means of two indicators: the trophic level and the vulnerability to fishery landings. Indicators showed a statistically significant decreasing trend in vulnerability and trophic level, suggesting that the fishery is increasingly targeting species of low vulnerability and trophic level, thus moving down the food web. The overall pattern of indicators was not uniform in space. Incidence interaction of gears and species landed explained the trajectory of indicators at the scale of Departments. Fishing gears targeted different levels in the food web, with gillnets responsible for the bulk of landings. Compared to a previous study, the group of fish species supporting most of landings has changed towards species with lower vulnerability, i.e. resistant to fishing mortality due to their evolved life-history but still of predatory habits in general. A notable exception is Mugil incilis, a species with a low trophic level that has become third in importance of landings in the database.

Population parameters of the clam Ameghinomya antiqua from the northwest of San Matías Gulf at the beginning of the fishery

Paula C. Zaidman, Fracisco E. Surdo, Rocío Velasquez, M. Socorro Doldan — Mon, 29 Jan 2024 00:00:00 +0000

Population parameters are fundamental when a new resource is incorporated into a fishery. Ameghinomya antiqua has recently begun to be collected for commercial purposes on the northwest coast of San Matías Gulf. This work aimed to analyze the population structure and describe the individual growth of A. antiqua specimens from two local populations (El Sótano and Playa Villarino) prior to the beginning of their exploitation. Organisms of each population differed in size and shell weight, as reflected by the general structure and the measures of central tendency. Age structures were also dissimilar: El Sótano presented long-lived individuals (over 18 years old), while the population from Playa Villarino was characterized by individuals younger than 15 years. The species showed an accelerated growth during the first years, reaching 90% of the maximum size at 5 years of age. The estimated maximum age was 26 years. The asymptotic height was greater in Playa Villarino (56.56 mm) than in El Sótano (53.03 mm). These populations have biological and population characteristics that suggest that sustainable management of this species could be carried out by incorporating it into the pool of benthic resources of the artisanal fleet of San Matías Gulf.

Aqua perspectives: stakeholder attitudes and perceptions in live fish transportation practices within the Kenyan fisheries sector

Wed, 14 Feb 2024 00:00:00 +0000

Live fish are in high demand all over the world, especially in China, where quality standards align with consumer preferences. In Kenya, discussions on live fish, particularly in aquaculture-rich regions, are focal points. However, the lack of a systematic approach to transporting live fish poses challenges for stakeholders. This research explores attitudes and perceptions of stakeholders in Kenya regarding the adoption and transportation of live fish, shedding light on transportation procedures and sector challenges. Using a descriptive research design, primary data were collected from diverse aquaculture stakeholders through a questionnaire, addressing their knowledge, perceptions, and attitudes toward live fish transportation in the country. The study unveils varied patterns of live fish transportation in Kenya, influenced by the purpose and distance. Private cars are prominent at 26.3%, with Nyanza and Mombasa leading at 35%. Modified vans are prevalent in Central-Nairobi and Western regions (25% and 22.5%, respectively), while public transport is widespread, especially in Central and Nairobi (25%). Purpose-built live fish vehicles dominate in Western and Nyanza (20% and 17.5%, respectively). Crustaceans like lobsters and crabs are primarily exported from the Coastal region (27.5%). Participants generally assessed their knowledge of live fish transportation as moderate, with a basic understanding of fish welfare. Feedback indicates common practices in live fish transport in Kenya as sealed tanks, plastic bags, and purpose-built vehicles. Temperature and oxygen fluctuations poses a significant challenge during transportation across all regions, particularly in Mombasa and Kisumu. The use of anaesthetics, especially for food fish, is infrequently reported. The study revealed favourable perceptions of stakeholders to live fish transportation and welfare, indicating early adoption. Further research is recommended on fish welfare, best management practices, technological advancements, and interdisciplinary studies to enhance the sustainability of live fish transportation sector and fish welfare in Kenya.

Validation and automatic detection of the dispersive transport of the submarine outfall of Mar del Plata, Argentina

Tue, 30 Jan 2024 00:00:00 +0000

The submarine outfall of Mar del Plata city at Camet was projected considering the mean and maximum of forecasted sewage discharges, the inner-shelf depth, coliform concentration and its decay (T90) mainly induced by sunlight effect and costal salinity. In 2016 the outfall was operating with a length of 3,810 m and diffusers in the last 526 m. An economical method to monitor its performance in relation to the surroundings, is remote-sensing techniques, applying either visible or radar images. Tidal currents parallel to the coast are responsible for the transport of the sedimentary plume in the far field, after a primary dilution from a depth of 11 m. Visible images (1.5 to 6 m spatial resolution) are effective in monitoring the plume entrained in the upper portion of the water column. These analyses led to study the interaction between waves and coastal currents. Radar images (30 m resolution X and C bands) permit to survey the slick-alike plume that differs from the environment water by the surface roughness. Comparing both techniques visible images can distinguish the different colours of the plume; instead, the radar images are showing the surface roughness from the slick-alike plume. The main advantage of active sensors is that they can map the plume during a cloudy weather and even during night time.

Antimicrobial resistance: a concern related to streptococcosis in tilapia farming

Marco Shizuo Owatari, José Luiz Pedreira Mouriño, Maurício Laterça Martins — Mon, 19 Feb 2024 00:00:00 +0000

Despite all the technical-scientific knowledge about streptococcosis, the high prevalence of bacterial infections caused by Streptococcus spp. in Nile tilapia farming implies the frequent, often irresponsible, use of antibiotics. The use of chemotherapy in aquaculture environments remains an efficient practice in the treatment of bacterial infections and disease prevention. Research have shown that the emergence of antimicrobial resistance (AMR) in farmed fish is one of the main challenges faced in aquaculture. It is known that emerging AMR in aquaculture can be transferred to clinically important strains from the natural environment through horizontal gene transfer (HGT) affecting the entire aquatic ecosystem. Maintaining health in tilapia farms promotes the sustainability of production systems and, consequently, improves the final quality of farm products. Therefore, the objective of this review was to provide information on the prevention, control and eradication of diseases in Nile tilapia farms, and how such management plays a fundamental role in maintaining public health by ensuring adequate sanitary conditions for animals intended for human consumption.

Modal and empirical lengths at sexual maturity for six deep-sea species in Ecuadorian oceanic waters

René Zambrano, Dialhy Coello, Marco Herrera — Thu, 16 Nov 2023 00:00:00 +0000

The objective of the present work was to establish modal lengths, empirical lengths at sexual maturity, and proportions of mature individuals of six deep-sea species from the bycatch of the experimental fishery for Patagonian toothfish (Dissostichus eleginoides). Fishing was conducted in Ecuadorian oceanic waters by only one vessel, between 2017 and 2021. Modal lengths were identified using frequency distributions. The length at sexual maturity (L_m) was estimated using the empirical equation: Ln L_m = -0.1189 + 0.9157 * Ln (L_max). Modal lengths presented a little annual increment in Antimora rostrata and Coryphaenoides armatus while the values decreased for Centroscymnus owstonii, C. delsolari, and Hydrolagus melanophasma. Interannual lengths were similar for Etmopterus granulosus. Modal lengths were higher than the sexual maturity length for H. melanophasma, C. delsolari, C. owstonii and A. rostrata. Furthermore, Coryphaenoides armatus showed a similar value and E. granulosus a lower modal length. Empirical length at sexual maturity was between 56.35 and 66.26 cm TL for all species except for H. melanophasma, which was 100.53 cm TL. Antimora rostrata and C. armatus presented an increment of mature individuals while the annual percentage decreased for H. melanophasma, C. owstonii, and C. delsolari. Etmopterus granulosus showed a lower proportion of mature individuals.

First DNA barcoding-based record of Lysiosquilla maculata (Crustacea: Stomatopoda) from Chennai coast, Tamil Nadu, India

Chelliah Babu; Krishnan Silambarasan, Antony P. Anrose, Antony P. Tiburtius — Tue, 05 Dec 2023 00:00:00 +0000

The taxonomic identification of mantis shrimp Lysiosquilla maculata was performed through DNA barcoding analysis of specimens collected from the Kasimedu fishing port, Chennai coast, Tamil Nadu, India. The mitochondrial cytochrome oxidase subunit I (mtCOI) gene with a region of 650 bp was sequenced for phylogenetic analysis. In the present record, mitochondrial gene sequences were used to identify the mantis shrimp. This is the first confirmed DNA barcoding record from Indian waters, whose mtCOI sequence was deposited in GenBank. The Neighbor-joining method was used for phylogenetic analysis. The calculated pairwise genetic distance with five closely related species ranged from 0.01 to 0.094%. The morphological and molecular analysis confirm that the specimens collected correspond to L. maculata.