Radiotagging a long-distance migratory characid fish: reproduction after surgery, tag losses, and effects in weight

Alexandre Peressin,Alessandra Gomes Bedore,Paulo Santos Pompeu,Carlos Bernardo Mascarenhas Alves,Ivo Gavião Prado,João de Magalhães Lopes

doi:10.1590/1982-0224-2020-0097

Alexandre Peressin, Alessandra Gomes Bedore + Show 4 more

Open Access

https://doi.org/10.1590/1982-0224-2020-0097

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Abstract

Abstract Although biotelemetry studies bring useful information, tagging is a highly invasive procedure. For this reason, we assess if intracoelomic tagging alters survivorship, weight gain and/or reproductive capacity of a neotropical migratory fish. In August 2016, 60 fish were equally and randomly distributed among 3 treatments: Control (anesthesia), sham surgery (anesthesia and surgery), and true surgery (anesthesia, surgery and tagging). Surveys for weight and tag expulsion were performed periodically from surgery through spawning (November/2016), with a final survey occurring in May/2017. Mortality was higher in true surgery (25% died) and for males. Twenty percent expelled tags, and initial weight loss followed by gain were verified for all treatments. Females of all treatments spawned, and fecundity and fertility were not different. Then, future studies should consider the losses due to death and tag expulsion when defining the sample number. We also encourage further investigations about differences in mortality between sex and weight variation, as well as any other factor that leads to increase in mortality. This is the first study that investigated tagging effects in reproduction of neotropical fishes, and since the methods and tags used are not species-specific, we infer that similar effects could occur in other species.

Highlights

In the book “Fisheries Techniques” published by American Fisheries Society (AFS) in 1983, and again in the 2nd edition (1996), J.D.Winter recommended that “Fish generally should not be equipped with transmitters that weigh more than 1.25% in water or 2% in air of the fish’s weight out of water”
The transmitter will affect the buoyancy of the fish, and the ability of the fish to compensate for the additional mass is important for the discussion of maximum tag/bm ratios
The results showed that even fish with a tag representing 10% of the body mass were able to compensate for the transmitter by filling their swim bladders, but the following increase in air bladder volume affected the ability of the fish to adjust buoyancy to changes in pressure

Summary

Introduction

In the book “Fisheries Techniques” published by American Fisheries Society (AFS) in 1983, and again in the 2nd edition (1996), J.D.Winter recommended that “Fish generally should not be equipped with transmitters that weigh more than 1.25% in water or 2% in air of the fish’s weight out of water”. The estimated estuarine mortality for fish tagged with the larger acoustic tag (70%) was almost identical to that for fish tagged with a radio tag (64%), suggesting that the size of the transmitter had a minimal and not statistically significant effect on predation (Clements and Schreck, 2002).

Results

Conclusion