Fish Landings Research Articles

Phylogeographic Insights of Five Co-Habiting Grouper Species in The Indo-Malaya Archipelago

Understanding the patterns of genetic diversity of species and precise stock identification are important in fisheries conservation management. However, studies on genetic diversity, connectivity, population structure, and gene flow of groupers within the Indo-Malaya Archipelago (IMA) waters are limited. The objective of the present study was to examine the phylogeographic patterns of the family Epinephelidae in IMA waters based on a parallel study of five selected species utilizing the mitochondrial COI. The grouper species were: areolate grouper (Epinephelus areolatus), blacktip grouper (Epinephelus fasciatus), six-bar grouper (Epinephelus sexfasciatus), blue-lined hind (Cephalopholis formosa), and white-edged lyretail (Variola albimarginata). Specimens were obtained from fish landing sites and fish markets from 23 locations throughout the IMA waters. This study showed genetic structuring for two species (Epinephelus areolatus and Variola albimarginata) but genetic homogeneity for the other three investigated species across IMA. Various geological and demographic histories, local and regional oceanographic features, and biological characteristics are hypothesized to shape the present genetic pattern of each species across the IMA waters. The establishment of effective international cooperation is encouraged to manage grouper species stocks in this region.

The Pattern of Coastline Changes and Wave Modelling around the Expansion of PPI Popoh Tulung Agung, East Java

The expansion of the Popoh PPI in Popoh Village, Tulungagung, East Java affects the movement of currents and waves in the vicinity. The purpose of this study was to analysis sediments and the pattern of coastline changes and to elaborate these using wave modelling based around the expansion of the Fish Landing Port Popoh. The methods used in this research were sieve analysis, remote sensing and GIS for processing Sentinel-2 imagery, and hydrodynamic modeling using DHI MIKE 21. Sediment sampling was carried out based on a purposive sampling method, with 10 points spread over land and water using a sediment grab. The findings of the study showed that there was a fairly large accretion from 2015 to 2021, with sand and clay sediment types. The accretion process dominated the abrasion process at Popoh Beach. In the period 2015 to 2018, the area of ​​accretion was 17.78 hectares and, in the period 2018 to 2021, the area of ​​accretion was 9.32 hectares, so that for 6 years there was an accretion of 18.79 hectares. The average wave energy was 1.5 kW/m per year on eroded beaches with sandy sediments. Highlights A sizable increase in land area from 2015 to 2021 with sand and clay sediment types The area of ​​increase in the 2015 - 2018 period was 17.78 hectares and in the 2018 - 2021 period it was 9.32 hectares The beach accretion process is more dominant than the beach abrasion process in Popoh Beach The average wave energy of 1.5 kW/m per year has eroded the sandy beaches of Popoh Beach

Comparative Study of Sediment Transport using the Caldwell and Cerc Methods at the Donggala Fish Landing Base

Donggala Fish Landing Port (PPI) is a fish port located in Central Sulawesi, precisely in Labuan Bajo Village, Banawa District, Donggala Regency, which is located along the high seas coast. The change in shoreline at the Donggala Fish Landing Base is caused by sediment transport that occurs due to wind and incoming waves. This study aims to determine the sediment characteristics, the amount of longshore sediment transport that occurs per year, and the ratio of the amount of sediment transport for 10 years using the Caldwell method and the CERC method. Analysis of sediment characteristics was carried out by testing carried out in the laboratory with the analyzed parameters, namely: sediment density, sediment grain size distribution and sedimentation velocity. There are many methods that can be used to calculate sediment transport, including the Caldwell method and the CERC method. The results of the sedimentation analysis, it is found that the sediment fraction is sand with various diameters, namely ϕmin = 0.075 mm and ϕmax = 25 mm, sediment density γmin = 2,604 g/cm3 and γmax = 2,678 g/cm3 and sedimentation velocity Wmin = 0.251 m/s and Wmax = 9,946 m/s. From the calculation of sediment transport analysis using the Caldwell method, the maximum amount of sediment transport that occurred in 2009 was 0,956 m3/year and for the CERC method, the maximum amount of sediment transport occurred in 2009 was 0,210 m3/year. The calculation of sediment transport analysis that was reviewed for 10 years, the value obtained by the Caldwell method Qs = 3,353 m3/year, while the CERC method Qs = 0,705 m3/year so that the amount of sediment transport using the Caldwell method is greater than using the CERC method.

Trawl Fisheries in the Gulf of Thailand: Vulnerability Assessment and Trend Analysis of the Fish Landings

Vulnerability of each stock in the catches from trawl fisheries in the Gulf of Thailand was assessed by productivity susceptibility analysis. Separate assessments were made based on type of trawler (otter-board, pair and beam) and vessel size (SS, S, M, L and XL, according to gross tonnage). Catches were distinctly different among trawler types and were dominated by demersal fishes, pelagic fishes and shrimps in the otter-board, pair and beam trawlers, respectively. The stocks of over 200 taxa were included in the study; high-vulnerability taxa were found for all trawl types and sizes, except the beam trawler size S. Only seven (7) taxa were classified as high vulnerability, including four (4) teleost taxa, namely Saurida elongata, Plotosus spp., Gymnothorax spp. and Sphyraena spp., and three (3) elasmobranch taxa, namely Carcharhinus spp., Brevitrygon heterura and Neotrygon kuhlii. Meanwhile, as many as 26 high-medium vulnerability taxa were found in catches by otter-board trawler size L, which included not only fishes but also cephalopods. Trends and variation in fish landings of 20 high and high-medium vulnerability taxa were analyzed. Eighteen (18) taxa showed monotonic trends, both continuous and discontinuous, in their time series of annual landings, but not Muraenesox spp. nor Uroteuthis spp. The long-term variations in fish landings ranged mostly between 40% and 50%. The short-term variations showed positive absolute and relative skewness, i.e., mostly between 10% and 20%. Results of this study highlight the taxa that require a precautionary approach for fishery management and warrant comprehensive fish stock assessment. Such data will allow more accurate determination of their status compared to the reference points and facilitate better management of trawl fisheries in the Gulf of Thailand.

Raining Season Ecological Survey of Artisanal Fish Landings in Tungbo, Bayelsa State, Niger Delta

Raining Season Ecological Survey of Artisanal Fish Landings in Tungbo, Bayelsa State, Niger Delta

Gendered spaces and entanglements: analysis of fisher couples’ decision-making and practices in Ghana’s Western region

This paper seeks to examine the agentic role of the physical spaces (e.g. landing beach, fish market and fish processing kitchen) within which fishery tasks are undertaken as they entangle with human, non-human, and discursive forces to co-create gendered subjectivities in fisher couples’ decision-making and practices. The paper is based on larger ethnographic study on fisher couples’ decision-making and practices in Ghana’s Western region, using participatory ethnographic observation including photo elicitation, vignettes and 38 in-depth interviews. Findings from the study indicate that the fish landing beach (consisting of sea water and sandy coast) played active roles in the kinds of tasks men and women could perform. The ability of the sea water to wet women’s long dresses, coupled with their menstrual body and discourse of women as unclean worked together to limit women’s ability to engage in activities, such as fishing. In terms of fish processing and trading, the study showed that the enclosed nature of fish processing kitchen served as a protective force which prevented public scrutiny of couples’ household practices to allow for husbands to help their wives in fish processing and storage. In instances of disagreement, the bedroom played a protective role where couples settled their differences on somewhat equal ground. Tracing the agentic and constitutive role of spaces, shift our focus from a purely social understanding of gender towards a holistic view of the multiple and complex pathways through which the environment and matter combine with discourses to co-create continuous and flexible (re)iterations of gender emergences.

DNA sequencing shows that tropical tuna species misidentification can be an underestimated issue in fish landings

Taxonomic identification of food is a key component to the correct implementation of traceability pipelines during fish processing. Genetic methods have increased exponentially our discrimination power at the species level. In this context, sustainable management of tuna fisheries can clearly profit from the implementation of this kind of quality control procedures, although they are more difficult to implement at the earlier stages of tuna processing, from harvest to the arrival of fish landings at a processing plant. Here we provide a case study using tuna landings to a processing plant in Cabo Verde, an important small island developing State, which supplies mainly the European Union region. Using DNA sequencing based species identification of tissue samples, we found a taxonomic miss-assignment of species identity in 33% of the individuals in the three target tuna species, Bigeye ( Thunus obesus ), Yellowfin ( Thunus albacares ), and Skipjack ( Katsuwonus pelamis ). More than half of Yellowfin samples were wrongly assigned as bigeyes or skipjacks. We also found that many bigeyes were wrongly assigned as yellowfins or skipjacks. None of the skipjacks were incorrectly assigned. The proportion of Yellowfin samples incorrectly assigned as bigeye was significantly higher than the samples of bigeye incorrectly assigned as yellowfins. These results clearly prove the need for improved traceability processes, which should encompass the whole processing pipeline, from harvesting to the consumer. • DNA sequencing found issues of species traceability on tuna landings in Cabo Verde. • Miss-assignment of species identity occurred in 33% of the tuna individuals. • Miss-assignment did not occur in Skipjack tunas, only in Yellowfin and Bigeye tunas.

ANALYSIS OF THE LEVEL OF WELFARE OF THE FISHERMAN COMMUNITY AT THE VILLAGE FISH LANDING BASE TANJUNG LUAR, EAST LOMBOK

This service aims to determine the level of welfare of fishing communities in East Lombok. This service was carried out for fishermen at the Tanjung Luar Fish Landing Base, East Lombok Regency, West Nusa Tenggara. The sample in this study is 15% of the total fisherman population in the base area. Data collection technique used is interview. The data analysis technique used was descriptive qualitative analysis. The results showed that the welfare level of the fishing community was 52 respondents (54.1%) belonging to the poor, 36 respondents (37.5%) belonging to the prosperous I, and 8 respondents (8.3%) belonging to the prosperous II. If it is related to the 2022 East Lombok Regency Minimum Wage, which is Rp. 2,372,532, then all respondents fall into the poor category, the income of the pre-prosperous people is Rp. 897,000, the prosperous people I Rp. 1,149,000, and the prosperous people II Rp. 1,470,000.

Biological aspects, exploitation rates, and spawning potential ratio of scalloped hammerhead shark (Sphyrna lewini Griffith & Smith, 1834) in Lampung Bay waters, Indonesia

The scalloped hammerhead shark is an endangered species that is listed in CITES Appendix II. Information on the biological aspects, exploitation rate, and spawning potential ratio of scalloped hammerhead sharks are very limited, especially in Lampung Bay waters. These data were important to find solutions and the best management to sustain the scalloped hammerhead sharks in Indonesia, especially in Lampung Bay waters. The aim of this study is to investigate the biological aspects, exploitation rates, and spawning potential ratios of scalloped hammerhead sharks in Lampung water. Scalloped hammerhead shark samples were collected from the catch of bottom gillnet in Kalianda Fish Landing Place, Lampung Province. Enumerators collected biometric data (length and weight) of 332 scalloped hammerhead sharks from July to November 2020. Biological aspects include distribution of length, length-weight (L-W) relationships, length at first capture, and length at first maturity. The utilization rate was calculated using the exploitation rate (E) and the estimated SPR based on length data. The results show that the length of scalloped hammerhead sharks ranged from 37.5 to 173.0 cm FL. Most of the samples fish had not spawned yet or were immature (Lc =47.1 cm FL; Lm =89.4 cm FL). The growth pattern of scalloped hammerhead sharks was allometrically negative. Scalloped hammerhead sharks have natural mortality of 0.18/year, while fishing mortality was 1.08/year. The fishing status of scalloped hammerhead sharks in Lampung Bay was fully exploited (E=0.85), and the stocks were in a recruitment overfishing condition. These findings indicate that effective management is required to ensure the sustainability of scalloped hammerhead sharks in Lampung Bay waters, such as adjusting mesh size, fishing season, and avoiding capture in the nursery area.

Sustainable Livelihood of Fishers in Palangpang Beach, Sukabumi, Indonesia

Ciletuh is an areas in Sukabumi which was inaugurated as Global Geopark by UNESCO in 2017, and has many potential natural resources. The high number of visits at Palangpang Beach, Ciwaru Village, is an opportunity for fishermen in Ciwaru Village to participate in activities involving fishermen in the marine tourism sector but this is inversely proportional to the infrastructure development at the Ciletuh Geopark. So, it is important to analyze sustainable livelihood of fishermen before and after the development of the Ciletuh Geopark. The research methods used are descriptive analysis, and sustainable livelihood analysis. The results show that sustainable livelihood assets of fishermen who increasing were human capital, social capital, physical capital, and economic and financial capital, while natural capital experienced a decline in assets due to the accumulation of garbage on the shore and in the sea that interferes with fishing activities. Finally, The local government and the management of Auction Place of Fish of Ciwaru have made improvements to fishery support facilities, in the form of parking lots for fishing boats and more adequate fish landings for fishermen, but the government needs to manage the garbage on the beach area.

Retained fish catches of artisanal fishers is dependent on fishing area, season and fishing gear type: A case study from the south coast of Kenya

The artisanal fishery is one of the sources of livelihood along the Kenya coast. Catches of retained fish of artisanal fishers between two fishing areas on the south coast of Kenya were compared. Artisanal fishers usually retain a portion of their daily catch which is reserved for family consumption while the rest is traded for cash to meet other family needs. This study hypothesized that retained fish catches were influenced by fishing area, fishing gear type and season. Daily fish landings and retained fish catches among artisanal fishers were monitored between August 2020 to July 2021 covering the South East Monsoon (SEM) and North East Monsoon (NEM) in Msambweni and Vanga fishing areas. A total of 60 fishers (30 for each area) were randomly selected and their retained catch monitored on a daily basis. The overall total fish landings were 23.3 tons and 210 tons in Msambweni and Vanga, respectively. The mean catch rate at Msambweni was 3.3 ± 0.12 kg.fisher-1day-1 in the NEM season and 2.2 ± 0.09 kg.fisher-1day-1 in the SEM season. Fish catch rates in Vanga was 8.5 ± 0.28 kg.fisher-1day-1 in the NEM season and 7.9 ± 0.29 kg.fisher-1day-1 in the SEM season. A total of 0.98 tons (only 4.2 %) of fish was retained versus 22.32 tons (95.8 %) not retained by the artisanal fishers in Msambweni, while in Vanga a total of 1.64 tons (only 0.78 %) was retained versus 208.36 tons (99.22 %) not retained. Retained fish catch varied significantly with season and type of fishing gear used (p < 0.05). Among the retained species in Msambweni, Siganus sutor made the highest contribution (53 %), followed by Lethrinus mahsena, (5.08 %). The species Euthynnus affinis and Sphyraena obtusata were mostly retained in Vanga with a contribution of 10.4 % and 10.2 %, respectively. The same retained fish species represented the most abundant species in the overall fish landings, however sizes were significantly smaller than those not retained by fishers (p < 0.05). Results of non-Metric Multidimensional Scaling (nMDS) ordination showed differences in species composition between fishing areas, seasons and fishing gear types with implication on fishers’ retained catches.

Modelling relationships between fisheries landings and oceanographic variables: A case study in adjacent areas of Gibraltar Strait

Small pelagics are one of the most important groups of fishes in the world due to their ecologic significance in the trophic web. Small pelagics are the main target of the world’s fishery industry and European anchovy, European sardine, mackerel and horse mackerel represent 43.7% of the total landings in Andalusia (southern Spain). The main objective of this study was to analyse the different factors that could be affecting the abundance of these small pelagics in the two main andalusian fishing areas: Gulf of Cadiz and North Alboran Sea. For this purpose, multiple Generalised Additive Models (GAM) were performed using different oceanographic variables and landing time series as explanatory variables. The explanatory variables were also included with up to a three-year lag. A total of 4776 partial models were performed and eight models (the best for each species per area) were extracted for analysis. GAM models explained up to 61% of the total variance. Most of the models showed a strong non-linear relationship between different fish landings, and all models showed primary production as a key environmental factor to explain variations in the abundance of these small pelagics. However, results also revealed differences in the fishing pressure for all species in both fishing grounds. The use of non-linear models as an analytic tool could be useful for improving the knowledge on small pelagics and the management of the small pelagics fishing industry.

Mineral Composition of Important Shell Fish Species from the Escravos River Estuary, Delta State, Nigeria and their Nutritional Significance

This study was conducted to evaluate the mineral composition (phosphorus, sodium, potassium, magnesium, calcium, iron, copper, manganese and zinc) of important shell fish species from the Escravos River Estuary, Delta State, Nigeria. A total of five shell fish species including the Pink shrimp (Peneaus notialis), Tiger shrimp (Peneaus monodon), Blue crab (Callinectes amnicola), Perewinkle (Tympanostonus fuscatus), and Mangrove oyster (Crassostrea gasar) were collected and used for the study. The shell fishes were collected from the fish landing sites of the estuary between March 2022 and June 2022 and analyzed for mineral composition following standard methods. The findings of this study showed that all the shell fish species evaluated were rich in minerals including phosphorus (P), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), copper (Cu), manganese (Mn) and zinc (Zn) which varied significantly (P<0.05) among the shell fish species. This is the first study to evaluate the mineral composition of important shell fish species that are of particular public health significance in the Escravos river estuary. The findings of this study have provided baseline information or database of minerals in shell fishes from the Escravos River. Therefore, shell fish consumers within the Escravos river will be sufficiently knowledgeable on the mineral composition of each shell fish species examined with the flexibility of consuming the shell fishes according to their mineral need. Also, the mineral profile of these shell fishes would provide a guideline for nutritionists and medical practitioners in the prescription of diet charts for the inhabitants of the Escravos river estuary and beyond.

Characterization of the Iraqi Artisanal Marine Fisheries, Northwest of the Arabian Gulf

The study described the characteristics of the Iraqi artisanal marine fisheries in the northwest Arabian Gulf between January 2020 and December 2021. The study aimed to update knowledge on the fish landings of the artisanal marine fisheries in the study area. A total of 19,877 t of fish were landed in 2020 and 13,784 t in 2021. A Student’s t-test showed a significant difference between the species’ landings over the two years. The main species exploited were mullets (10.5%), threadfin bream (10.4%) and spotted leatherskin (8.4%) in 2020, whereas threadfin bream (14.2%), mullets (9.6%) and tigertooth croaker (8.3%) were mainly landed in 2021. Unfortunately, the contribution of river shad catches has dropped to lower levels over recent years, comprising 3.6-5.8% of the total landings during 2020-2021. Shrimps contributed 15.6 and 16.1% of the total landings during 2020 and 2021, respectively, and mixed fish contributed 11.8 and 15.3%, respectively. The trends of the landings of the main fish groups increased substantially from 2011 to 2021. Unfortunately, the contribution of river shad (T. ilisha) catches has dropped to lower levels over recent years, in contrast with the contributions of other species. Therefore, the study recommends the following management measures for the river shad stock: to protect the brood stock during the breeding season no fishing should be allowed in the Shatt Al-Arab River during the main spawning migration from May to June and small T. ilisha (<23.0 cm) should not be caught.

Insights on the use of dolphins (boto, Inia geoffrensis and tucuxi, Sotalia fluviatilis) for bait in the piracatinga (Calophysus macropterus) fishery in the western Brazilian Amazon

In the Amazon Basin, the use of the pink dolphin or boto (Inia geoffrensis) for bait in the piracatinga (Calophysus macropterus) fishery was first detected in the year 2000. Since then, this artisanal fishery has become more prevalent as it requires only a few hours of work per night and provides immediate cash earnings. It is thus an attractive addition to (or replacement for) traditional fishing. Previous reports have noted the use of botos as bait, but stated that the most common bait used are caimans (Melanosuchus niger, Caiman crocodilus). Estimates of the number of dolphins killed based on fish landings have been proposed and an apparent decrease in sighting/survival of an artificially-marked boto population was observed. Although stocks/population estimates, trends and actual numbers of hunted dolphins are unknown, the conservation impacts of this activity are of concern. Between October 2010 and November 2011, research was conducted within an area with serious conflicts between dolphins and fishermen as well as intense fishing for piracatinga, i.e. in the lower Japurá River, on the border with the Mamirauá and Amanã Sustainable Development Reserves, where both boto and tucuxi (Sotalia fluviatilis) are used for bait. One-hundred and fifty-seven monitoring surveys were carried out in eight key communities, confirming 114 piracatinga fishing events through direct monitoring and incognito surveys of fishing gear (gaiolas). Empirical evidence of the activity in gaiolas comprised pieces of bait, carcass remains, piracatinga provoked vomits and dolphin fished carcasses. Of those, 31.2% (n = 35) involved cetacean bait (91.4% I. geoffrensis, 8.58% S. fluviatilis), 68.7% (n = 77) caiman bait (96% M. niger, 4% C. crocodilus), and two fishing events used both types. These percentages may be higher/lower in other areas within and outside the Reserves. Given the increasing trend of the piracatinga fishery, the authors believe that precautionary measures for the conservation of Amazonian dolphins are urgently needed. Development of practical short-term solutions (e.g. offal-baited fish traps) and multispecies management together with law enforcement, incentives and educational programmes could allow the future transition of riverine communities from the piracatinga fishery to sustainable, higher income activities.

FISHERIES AND BIOLOGICAL INFORMATION OF BOTTLENOSE WEDGEFISH (Rhynchobatus australiae) IN PULAU KAMBING FISH LANDING PORT TERENGGANU

Rhynchobatus australiae is a species of wedgefish that is vulnerable to overfishing due to their life history characteristics This study aimed to determine the fisheries and biological information of R. australiae in Terengganu waters. A total of 26 fish were collected over a 3-month period in Pulau Kambing Fish Landing Port, Terengganu and analysed for abundance, length frequency distribution, LWRs, and growth parameters. Results showed that the abundance of R. australiae in Terengganu was higher compared to the estimation made in other locations, with a CPUE of 49.05 kg/haul and 9.15 kg/day. The LWRs for males, females, and pooled sexes were a = 0.0057 and b = 2.9404, a = 0.0018, b = 3.2078, and a = 0.0029, b = 3.0979, respectively. The von Bertalanffy Growth parameters for male, female, and pooled sexes of R. australiae were k = 0.035, L∞ = 332.825, t0 = -4.495, k = 1.005, L∞ = 43.161, t0 = -2.99, and k = 0.089, L∞=222.412, t0=-2.565, respectively. Males R. australiae exhibiting a higher average length than females. This study was limited in terms of the time span covered and the sample size, which may have introduced variability in the results and may not be representative of the larger fish population. However, the results of this study may serve as preliminary data for the fish population dynamics of R. australiae in Terengganu waters and could be used to guide future research. Future study with a longer time span and a larger, more diverse sample size are needed to estimate the abundance and size of R. australiae more accurately in this region.

Maximizing Use of Pelagic Capture Fisheries for Global Protein Supply: Potential and Caveats Associated with Fish and Co-Product Conversion into Value-Add Ingredients.

Globally, capture fisheries contribute significantly to protein supply and the food security of a third of the world's population. Although capture fisheries production has not significantly increased in tonnes landed per annum during the last two decades (since 1990), it still produced a greater tonnage of protein than aquaculture in 2018. Policy in the European Union and other locations favors production of fish through aquaculture to preserve existing fish stocks and prevent extinction of species from overfishing. However, aquaculture production of fish in order to feed the growing global population would need to increase from 82 087 kT in 2018 to 129 000 kT by 2050. The Food and Agriculture Organization states that global production of aquatic animalswas178 million tonnes in 2020. Capture fisheries contributed 90 million tonnes (51%) of this. For capture fisheries to be a sustainable practice in alignment with UN sustainability goals, ocean conservation measures must be followed and processing of capture fisheries may need to adapt food-processing strategies already used extensively in the processing of dairy, meat, and soy. These are required to add value to reduced fish landings and sustain profitability.

Morphometric and genetic variations of four dominant species of snappers (Lutjanidae) harvested from the Northern Coast of Aceh waters, Indonesia

Lutjanus commonly known as snappers are economical fishes in the world, including in Indonesia. They have high morphological similarities and are difficult to distinguish. Therefore, this study aimed to validate the taxonomic status and kinship of four dominant snappers harvested from the northern coastal waters of Aceh, Indonesia, namely Lutjanus bengalensis, Lutjanus kasmira, Lutjanus gibbus, and Lutjanus fulviflamma. The samples were collected from Pulo Aceh and Lampulo fish landings. A total of 60 samples of each species were used for morphometric analysis using the traditional morphometric approach, while five from each of them served as samples for the genetic analysis with the COI gene. Morphological analysis showed that the four fish species were categorized into 3 different groups, where L. bengalensis and L. kasmira were in the same group. The genetic analysis revealed that they were grouped into four different clades, but L. bengalensis and L. kasmira were located in the same sister clade, indicating genetic closeness. L. bengalensis, L. kasmira, L. gibbus, and L. fulviflamma had two, three, three, and four haplotypes, respectively. Based on the results, the COI gene successfully distinguished the four species of snapper, where L. bengalensis and L. kasmira had morphological and genetic similarities. Furthermore, L. fulviflamma had higher genetic diversity than the others.

Trophic Modelling of the Cross River Estuary Ecosystem, Nigeria

A trophic modelling of the Cross River estuary ecosystem was undertaken using Ecopath with Ecosim (EwE). Data were obtained from peer reviewed journals, monographs and stock assessment reports and used to construct the Ecopath model used to investigate the structure, function and system throughput of the estuary. These data included biological data such as biomass, production/ biomass, consumption/biomass, fish catch and diet composition of each species or functional group included in the model. The network analysis routine was used to estimate trophic levels and trophic interactions of functional groups, health condition and developmental stage, and food web features. Results of Ecopath model revealed three apical predators: Shark, Senegalese tonguesole, and Sea catfish. The ratio of total primary production to total respiration value of 4.182 revealed that the Cross River estuary is an immature ecosystem void of biological and ecosystem pollution and is at its early developmental stage. The mean trophic level of the catch of 2.186 for the system and the high gross food conversion efficiency (GE) of 0.300 for Macrobrachium spp and 0.292 for Penaeid shrimp, revealed high fishing pressure on the herbivores. The estuary ecosystem has a short food chain and low connectance index of 0.1879 which has phytoplankton being grazed upon by zooplankton which in turn are taken up by bonga. Model results and physico-chemical parameters showed that the Cross River estuary is still relatively pristine and immature ecosystem, void of organic pollution and with relatively low primary productivity as evident in relatively low nutrient concentration. The high value of ecotrophic efficiency (EE) of 0.993 for bonga and 0.991 for Macrobrachium spp indicate that the population of these animals are heavily exploited and predated upon in the estuary. Despite that this is a preliminary trophic model, it is clear that fish populations in the estuary are experiencing excessive fishing pressure; thus necessitating management measures to reduce pressure, while relevant data especially on fish diet composition and fish landing should be collected in order to get improved model parameterization in the future.

Historical synthesis of fish landings from a market in Santarém-PA: trends for re-gional fisheries monitoring in the lower Amazon

Historical synthesis of fish landings from a market in Santarém-PA: trends for re-gional fisheries monitoring in the lower Amazon