Preservation causes shrinkage in seahorses: implications for biological studies and for managing sustainable trade with minimum size limits

Abstract

ABSTRACT1. The implications of shrinkage associated with desiccation and ethanol preservation for seahorses (genus Hippocampus) were investigated using Hippocampus guttulatus (European long-snouted seahorse) as a model. Specifically, this research addressed the implications of preservation for taxonomy and life history studies and the application of minimum size limits (MSL) for managing seahorse trade.2. In 2004, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) listed all seahorse species on its Appendix II, and recommended a 10 cm MSL as an interim means of ensuring sustainable international trade. Inconsistencies in seahorse measurement methods and repeatability posed challenges for applying the MSL. Moreover, the shrinking effect of desiccation on body length observed in other fish was assumed to be negligible for seahorses because of their high degree of ossification.3. Changes in seahorse sizes were measured following immersion in ethanol and desiccation. H. guttulatus shrank on average by 0.1-2.3% when preserved in ethanol and 3.0-6.4% when dried, depending on the trait measured. Similar trends were observed in a sample of H. kuda (yellow seahorse). Specimen posture during drying, and measurement methods also influenced estimates of size.4. Based on the shrinkage observed, 14-44% of captured seahorses that are dried could shrink to below the recommended MSL, even if all seahorses were longer than the MSL at capture. This demonstrates that small changes in body lengths can have significant implications for trade of species managed with size limits.5. Recommendations are to (1) standardize seahorse measurement methods, (2) consider the effects of preservation and measurement technique on body lengths, and apply appropriate corrections in comparative studies and when developing fisheries management strategies, and (3) adjust size limits at the point of capture to ensure retained seahorses comply with the CITES recommended MSL.

A Computational Study of the Hydrodynamics in the Nasal Region of a Hammerhead Shark (Sphyrna tudes): Implications for Olfaction

“…As discussed by Abel et al [3], the gap may conceivably have arisen in the present specimen as a result of clumping of the olfactory lamellae when the micro-CT scan was acquired in air, or due to postmortem shrinkage of the lamellae caused by preservation of the specimen [14]. However, the gap was clearly present in the MRI data, which was acquired in degassed water and avoided clumping of the lamellae.…”

Functional morphology of the nasal region of a hammerhead shark

“…It was collected by trawl off the coast of Guyana in 1959 and has been preserved in 70 % industrial methylated spirits, 30 % distilled water ever since. As a result, it may have experienced some shrinkage (Nadeau et al, 2009, and references therein). The specimen consists of the head and part of the gill region (Fig.…”

A synthesis of European seahorse taxonomy, population structure, and habitat use as a basis for assessment, monitoring and conservation

“…Comparisons of population structure among studies is also challenging because seahorse length can be measured by standard length ( L S ), total length ( L T ) or height (Lourie et al 1999a ) and previous studies have used all of these (e.g. Verdiell-Cubedo et al 2008 ; Nadeau et al 2009 ; Caldwell and Vincent 2012 ; Vieira et al 2014 ).…”