Fish availability in the coastal landing center highlights the assumption of stocks in the marine fishing zone of the ocean. This study, therefore, aimed to analyze the availability of marine fishes in the Bangladesh Fisheries Development Corporation (BFDC) landing center, Cox’s Bazar, Bangladesh between January 2021 and May 2021. A total of 54 species were recorded, of which 42 were marine fishes, 7 were shellfishes and 5 were large fishes. The dominant orders were Perciformes (56%), Scombriformes (17%) and Clupeiformes (10%). More than 56% of the total marine fishes were classified as Least Concern , nearly 10% were categorized as Near Threatened and 2% were marked Vulnerable . The dominant orders of shellfish were Portunidae (43%), followed by Penaidae (29%), Loligonidae (14%) and Octopopidae (14%). Shrimp Penaeous monodon had the highest consumer demand, whereas consumer demand for non-conventional shellfish was comparatively low. Most of the shellfish were categorized as Least Concern . Among large fishes, the wider availability of sharks (five species) and rays (two species) was observed in the winter and monsoon season, although the consumer demand for those large fishes was low. The Vulnerable sharks and rays were Sphyma zygaena and Mobula birostris . This study elucidates the present scenario of marine fishes in the BFDC fish landing center, Cox’s Bazar, Bangladesh.

Knowledge about fisheries market margins and fish availability in the market is crucial to establish an effective and well-planned marketing strategy. Hereby, the study was conducted to bring some knowledge on the availability of raw and processed fish and its marketing channel in Rajbari Sadar, Bangladesh from June to December 2020. Here, data were collected from fish traders and consumers of the target markets through questionnaire surveys, focus group discussions and field visits. The study found 107 fish and shellfish species in these markets, of which more than 50% species were commonly available and less than 10% were found very rarely. The study also observed 18 types of processed fish products in these markets including dried (77.77%), salted (16.67%) and fermented (5.56%) products arriving from mostly Dhaka and Chattogram. The markets were dominated by wild freshwater fishes of nearby rivers, ponds and canals etc. The length of processed and marine fish marketing channel was comparatively longer than freshwater one because these items are supplied here from coastal districts via several intermediaries. The study revealed remarkable market margin for hilsa fish even noticed up to 57.14% at consumer level. There was also observed some major constraints to a good marketing system such as unplanned market location, insufficient drainage system, high transportation cost, etc. Based on the constraints, the study would suggest to establish a well-planned and modern equipped fish market with high quality cold storage and ice factories, which could help to ensure smoother transaction route from production to customer minimizing economic loss.

Self-Organizing Maps (SOM) have been used for patterning and visualizing ten environmental parameters and phytoplankton biomass in a mactrotidal (>10 m) Gyeonggi Bay and artificial Shihwa Lake during 1986–2004. SOM segregated study areas into four groups and ten subgroups. Two strikingly alternative states are frequently observed: the first is a diverse non-eutrophic state designated by three groups (SOM 1–3), and the second is a eutrophic state (SOM 4: Shihwa Lake and Upper Gyeonggi Bay; summer season) characterized by enhanced nutrients (3 mg l⁻¹ dissolved inorganic nitrogen, 0.1 mg l⁻¹ PO₄) that act as a signal and response to that signal as algal blooms (24 µg chlorophyll-a l⁻¹). Bloom potential in response to nitrification is affiliated with high temperature (r = 0.26), low salinity (r = −0.40) and suspended solids (r = –0.27). Moreover, strong stratification in the Shihwa Lake has accelerated harmful algal blooms and hypoxia. The non-eutrophic states (SOM 1–3) are characterized by macro-tidal estuaries exhibiting a tolerance to pollution with nitrogen-containing nutrients and retarding any tendency toward stratification. SOM 1 (winter) is more distinct from SOM 4 due to higher suspended solids (>50 mg l⁻¹) caused by resuspension that induces light limitation and low chlorophyll-a (<5 µg l⁻¹). In addition, eutrophication-induced shifts in phytoplankton communities are noticed during all the seasons in Gyeonggi Bay. Overall, SOM showed high performance for visualization and abstraction of ecological data and could serve as an efficient ecological map that can specify blooming regions and provide a comprehensive view on the eutrophication process in a macrotidal estuary.

Sepiella inermis, spineless and small-size cuttlefish, is one of the important species of cephalopods and widely distributed in the Indo-west Pacific region. This study, for the first time in the southeastern region of the Bay of Bengal, Bangladesh, was conducted to investigate the length-weight relationship, condition factors and spawning season of S. inermis. Samples (∼149) were collected monthly from the Bangladesh Fisheries Development Corporation (BFDC) landing center, Cox's Bazar from July 25, 2022 to May 15, 2023. Females were dominant throughout the year. Female exhibited higher dorsal mantle length (DML, 6.56 cm) and body weight (BW, 41.55 g) than males. b value of the length-weight (DML vs BW) relationship of female and male was 1.912 (r² = 0.5072, p < 0.001) and 2.119 (r² = 0.9557, p < 0.001), respectively, which indicated a negative allometric growth pattern. The Fulton's, relative condition factors and relative weight fluctuated based on sexes and seasons. Five gonadal (immature, maturing, mature, spawning, and spent) and four testis maturation stages were observed. The highest percentage of mature females (100 %) and males (75 %) were observed between 10-10.99 and 9–9.99 cm DML, respectively. 50 % of the females and males matured at 7.2 cm and 5.2 cm DML, respectively. On average, females have a greater gonadosomatic index (6.87 %) than males (1.98 %). A major peak in GSI of females was observed in September 2022, and second peak was in January 2023. The major spawning season in males was observed during January and May 2023. GSI had a negative correlation with condition factors in females and males. Since this is the baseline study on the reproduction aspects of S. inermis, further study could consider the effects of oceanographic and climatic parameters on the abundance and reproduction of cuttlefish in the Bay of Bengal.