Pulpos: Una reproducción que les cuesta la vida

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Techniques for Estimating the Age and Growth of Molluscs: Cephalopoda

Global abundances and commercial fisheries of cephalopods have increased over recent decades, creating a need for effective fishery management. This management is often focused on the ability to ascertain the age structure of key populations. There are several main techniques for age and growth rate determination in cephalopods. Because of biological differences between species groups, not all techniques are applicable for every species. This review outlines the use of five main ageregistering structures (statoliths, gladii, beaks, stylets, and eye lenses) along with one chemical aging technique (lipofuscin) and their application to cephalopod species groups.En prensa1,04

Exploring the embryonic development of upper beak in Octopus vulgaris Cuvier, 1797: New findings and implications for age estimation

The beak of cephalopods (in particular octopods, where statoliths are not suitable) is a useful tool for age estimation and the aging method provides essential information on cephalopod growth and life cycles. These parameters are valuable in the assessment of population dynamics and stock management. The embryonic development of cephalopod beaks is poorly known. The presence of pre-hatching increments on the reading areas (rostrum and lateral walls) is unclear and there are no data on temperature influence. In this study, egg clusters of Octopus vulgaris were reared at 16, 19, 21, 23, and 26 °C. The extracted upper jaws were observed in order to validate the age of first daily increment formation, assessing the accuracy of age inferred from the two reading areas. Jaw dimensions were also measured in order to explore the development at different temperature conditions. The growth rate was calculated for beaks of rearing condition 21 °C, and the overall dimensions were compared among all incubation temperatures. Three ad hoc developmental stages are proposed for the upper beak of O. vulgaris embryos. Increments on lateral walls appear during the second phase, whereas the first increment on the rostrum is visible only at hatching. Consequently, only the accuracy of age inferred from the rostrum surface is confirmed for the early stages. The growth rate of the rostrum region accounted for a drop in growth during the third phase. Conversely, the growth rate increased until hatching in lateral walls, suggesting that the heterogeneity of the growth rate could be due to the different role played by the beak areas. Temperature influenced beaks in terms of overall size, as embryos reared at a warm temperature (23 °C) were smaller than the others. These results confirm that the incubation environment could alter hatchling characteristics thus affecting the recruitment conditions.Postprint1,58

Age and growth estimation of Southern Ocean squid Moroteuthopsis longimana: can we use beaks collected from predators’ stomachs?

Squid play a major role in the Southern Ocean food web. However, their age and growth remain poorly studied. Here, using upper and lower beaks of Moroteuthopsis longimana collected from the diet of Dissostichus mawsoni from Pacific and Atlantic sectors of the Southern Ocean, we studied: (1) Feasibility of using beaks collected from predators’ stomachs to study the age of Southern Ocean oceanic squid; and (2) Age estimation and growth patterns of M. longimana. The rostrum sagittal section (RSS) of both beaks had micro-increments, with the lower beak being the best to observe and count a readable sequence of increments to estimate the age. Assuming a daily deposition of increments, our results suggest that M. longimana can live up to 820 days and may hatch throughout the year. Studied individuals presented a consistent growth rate from hatching to death but with, at least, one period of faster growth. A novel pattern of regular cycles, composed of 7–10 lighter increments followed by a darker one, was found in the medium-anterior region of the RSS. Differences were found in the growth rate and size reached at the same age between individuals from the Pacific and Atlantic sectors, which might be related with different environmental conditions between both capture sites. This study shows that lower beaks from predators’ stomachs can be used to study the age of Southern Ocean squids and that M. longimana hatches in all seasons, being available year round to predators that feed of this species

Common Octopus Aquaculture in

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