Growth studies are important to determine the total recruitment of fish with respect to time while information on age and length at first maturity are essential to assess the spawning stock. The present communication deals with growth, maturity and mortality parameters of Indian oil sardine Sardinella longiceps from southwest coast of India. Length at first maturity of oil sardine was found to be 15.7 and 15.2 cm for male and female, respectively. Comparison of length at first maturity of oil sardine with earlier studies showed only minor variations. The growth parameters L ∞ , K, and age at zero length (t 0 ) were calculated as 19.8 cm, 1.14 yr -1 and -0.0464 respectively. From the VBG equation, the length attained at the end of I, II and III year is estimated as 13.79, 17.87 and 18.9 cm respectively. Two peaks of recruitment to the fishery were observed. The values of total mortality (Z), natural mortality (M) and fishing mortality (F) estimated are 4.33, 2.7 and 1.6 respectively. The exploitation rate was found to be 0.37.

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Age and growth of the little Indian squid Loliolus hardwickei (Gray, 1849) were studied using samples collected in the coastal waters of Arabian Sea. Statolith increment counts demonstrated that L. hardwickei has a fast growth rate (dorsal mantle length: 0.31–0.73 mm day−1 in females and 0.27–0.56 mm day−1 in males) and a short lifespan of less than 6 months. Females are the larger sex and their daily growth rates were higher than in males. The oldest male and female were 110 and 130 days old; the youngest mature female and male were 62 and 52 days old respectively. The oviducal fecundity ranged from 104–480 eggs, mean = 360 eggs (14–23 eggs g−1 body weight).

A bloom of the planktonic dinoflagellate, Ornithocercus magnificus was reported for the first time in the surface waters of the off Kochi coastal region with an evidently higher density of 1.7 x 10 6 cells L-1 on 18.12.2019. No conspicuous colouration of the surface waters was noticed even with the higher abundance of (1.7 x 10 6 cells L-1) observed near the barmouth area (6-7 m). The tracking on the occurrence of this genus in this region from 2013 to 2019 revealed their occurrence only during three times over the six years, i.e. the post monsoon season of 2013 and 2014 and during pre-monsoon of 2016. The SST of the three stations of the post monsoon season was compared for the last three years from 2017 to 2019, and an evident variation in the SST distribution was noticed in this region. The SST in 2019 was 2.1°C higher than that observed during 2017. The occurrence of Ornithocercus magnificus showed a positive correlation with SST (r s =0.425, p<0.05). It was also noted that the occurrence of this species was observed during the El Nino years. The Oceanic Niño Index (ONI) also positively correlated with the SST during the period (r s =0.432, p<0.05). The higher abundance of this species in 2019 when warmer SST was observed and their positive correlation with SST indicates the preferences of O.magnificus to warmer waters. The Shannon and Weiner diversity index (H') ranged from 2.87-3.29 and the water quality index (WQI) remained good during the bloom. As Ornithocercus magnificus did occur during higher SST, this genus can be used as a proxy of climate change and hence has a strong potential to be used as indicator species of higher SST variation if found in novel environments.

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