Age and growth of Antimora rostrata (Moridae, Gadiformes, Teleostei) from the Kerguelen and Crozet Islands in the southern Indian Ocean

Abstract

<jats:title>Abstract</jats:title><jats:p>Age and growth of blue antimora <jats:italic>Antimora rostrata</jats:italic> were examined for the first time in the waters of Kerguelen and Crozet Islands (southern Indian Ocean, sub-Antarctic). The longline catches were represented by fish ranging from 39 to 72 cm in total length with weights between 400 and 3310 g, aged 16– 41 years. A minimum age of 16 years was observed in a fish 39 cm long, while a maximum age of 41 years was recorded for an individual of 70 cm in length and 3310 g in weight. The age classes with the greatest numbers were represented by fish aged 34 years (9%), 28 years (9%) and 29 years (8%), which together accounted for 26% of the total catch. The blue antimora in the southern Indian Ocean shows similar growth rates to those of individual fish from the Ross, Lazarev and Weddell Seas and southeastern Greenland, which may indicate the population unity of the species within the Antarctic and sub-Antarctic waters or similar habitat conditions in these areas.</jats:p>

So Close Yet So Far: Age and Growth of Blue Antimora Antimora rostrata (Moridae, Gadiformes, Teleostei) off New Zealand and Macquarie Island (Southwestern Pacific Ocean)

“…In the Southern Ocean, the proportion of males in populations of the Lazarev and Weddell seas exceeded that of females at depths of 1100-1800 m [15]. Moreover, at depths ranging 800 to 2000 m in the Ross Sea, females made up to 90% of the catch [9], this corresponds well with the results of a study on Kerguelen and Crozet Islands (78% of females) [17]. In contrast to the latter data, in our catches males were more abundant than females (53.4% vs. 40.8%).…”

“…As it has been noticed in most studies [8,9,[16][17][18] determination of age for blue antimora is complicated by some uncertainty in interpreting the otolith zones, which we also have encountered in our study. In this publication we identify every visible ring as annulus similarly to our previous research in which age estimations remained invalidated.…”

“…Specimens from the Ross Sea varied in age from 11 to 41 years, while their New Zealand counterparts were from 4 to 28 years old [9]. The age of fish caught off southwestern Greenland was estimated from 7 to 38 years with a dominant share of individuals from 11 to 21 years [18], at the same time the catches from the Lazarev and Weddell Seas were presented mainly by 25-27-year-old fish [16] and 28, 29, and 34 year-old fish were most numerous (26%) off Kerguelen and Crozet Islands [17]. In the samples caught by our team, age distribution can be organized in the following groups: 32 years (13%), 29 years (11%) and 28, 33 and 34 years (9% each), totaling altogether in 47% of the catch.…”

“…A popular method of age estimation using otoliths, which was successfully applied to demersal (including deep-water) fish inhabiting waters along the west coast of the USA and Canada [27], is 'break and burn'. As species of genus Antimora, along with many other deep-sea fishes, can be probably considered as long-lived [8,9,[15][16][17][18][19][28][29][30][31], we used methods that were created exactly for long-lived deep-sea species [32].…”

“…Currently available publications on blue antimora don't provide any comprehensive information about its life cycle [6,7,[11][12][13][14]. A. rostrata aging and growth patterns have been studied in Icelandic waters [15], the Ross Sea and New Zealand waters [9], the Lazarev and Weddell seas [16], in waters surrounding Kerguelen and Crozet Islands [17], along with several areas of the North Atlantic Ocean, including waters off Flemish Cap, Greenland and the Mid-Atlantic Ridge [8,18,19]. However, the above publications did not include any 2 of 17 validations for provided age estimations.…”