Estimates of length-based population parameters of the skipjack tuna, Katsuwonus pelamis (Linnaeus, 1758) in the Andaman waters

The exploitation of Katsuwonus pelamis in Andaman waters is meagre compared to its total landings in India.  As the population parameters of this species has not been attempted in these waters, an attempt has been made here to estimate the population parameters of K. pelamis based on the length frequency data collected from local fishing boats operating from Junglighat Fishing Harbour, Port Blair, Andaman Islands from January to December 2014. A total of 704 specimens ranging from 16.5 to 71.0 cm fork length were taken for analysis. The parameters L∞, K and t0 were 74.55 cm, 0.59/year and –0.21 respectively. The von Bertalanffy growth equation for K. pelamis is Lt = 74.6[1 – e–0.59(t+0.214255)]. The recruitment pattern was unimodal. The recruitment period was from July – October. The longevity of the species was calculated as 4.9 years. After 1st, 2nd, 3rd and 4th year the length attained by the species is 38.1, 54.4, 63.4 and 68.3 cm respectively. The mortality parameters were Z=2.07, M=0.93, F=1.14 and exploitation ratio was 0.55. The virtual population analysis for K. pelamis indicated that fishing mortality starts at 41–50 cm class interval and it continues henceforth and was maximum at 61–70 cm and decreased thereafter

Arribazón de medusa azul Porpita porpita en las playas de Visakhapatnam, India (Bahía occidental de Bengala)

Porpita porpita occurs in the tropical and sub-tropical waters of the Pacific, Atlantic, and Indian Oceans, and the mass numbers of stranded colonies seem to be increasing. Although its presence in Indian waters is minimal, this is the first record ever made of P. porpita in Visakhapatnam coastal waters. The present study provided a detailed description of the species and its global distribution. Further, the perceived increase in gelatinous zooplankton blooms in the observed area indicates that jellyfish can negatively affect fisheries because they compete with zooplanktivorous fish, prey upon fish eggs and larvae, and indirectly compete with higher trophic levels by reducing the plankton available to planktivores. Conversely, jellyfishes also play a vital role in regulating global marine plankton food webs, spatio-temporal dynamics, and biomass, which is a role that has been generally neglected so far.Porpita porpita se encuentra en las aguas tropicales y subtropicales de los océanos Pacífico, Atlántico e Índico, y el número masivo de colonias varadas parece estar aumentando. Aunque su presencia en las aguas de la India es mínima, este es el primer registro de P. porpita en las aguas costeras de Visakhapatnam. El presente estudio proporcionó una descripción detallada de la especie y su distribución global. Además, el aumento percibido en las floraciones de zooplancton gelatinoso en el área observada, indica que las medusas pueden afectar negativamente a las pesquerías porque compiten con los peces zooplanctívoros, se alimentan de huevos y larvas de peces, e indirectamente compiten con niveles tróficos más altos al reducir el plancton disponible para los planctívoros. Por el contrario, las medusas también juegan un papel vital en la regulación de las redes alimentarias del plancton marino global, la dinámica espacio-temporal y la biomasa, un papel que generalmente se ha descuidado hasta ahora.  

On some commensal anomuran and brachyuran crabs (Crustacea: Decapoda) off Visakhapatnam, Northwestern Bay of Bengal

Silambarasan, Krishnan, Kar, Annada Bhusan, Prasad, Gummadi Venkata Ankineedu, Pattnayak, Sujit Kumar, Das, Pratyush, Reddy, Dwarampudi Bhami, Ramalingam, Lakshmana Perumal (2023): On some commensal anomuran and brachyuran crabs (Crustacea: Decapoda) off Visakhapatnam, Northwestern Bay of Bengal. Zootaxa 5325 (4): 541-555, DOI: 10.11646/zootaxa.5325.4.5, URL: http://dx.doi.org/10.11646/zootaxa.5325.4.