Abstract
BackgroundPassive integrated transponder (PIT) tags are commonly used to identify individual fish. However, use of PIT tags in commercial aquaculture research is limited by consumer safety concerns. For farmed fish, it is critical that tags do not end up in the final product. One possibility to enable the use of PIT tags in commercial research is to insert tags into a part of the body that will be separated from the trunk during processing. We compare tag loss, mortality rate and welfare scores between Atlantic salmon post-smolts (n = 798) marked with PIT tags either in the operculum musculature or the abdominal cavity (standard practice) before and after mechanical delousing.ResultsWe found that neither condition factor (K) (range 0.60–1.99) nor tagging location significantly affected tag loss (operculum = 6%, intraperitoneal = 8%, z = 1.46, p = 0.14) or mortality (operculum = 2%, intraperitoneal = 2%, z = 0.55, p = 0.58). However, on average, the fish which died weighed 20% less at the time of handling (271 ± 13 g, K = 1.12 ± 0.02) than those which survived (340 ± 3 g, K = 1.14 ± 0.004), and those which lost tags (291 ± 7 g, K = 1.11 ± 0.02) weighed 15% less than those which retained them (340 ± 3 g, K = 1.14 ± 0.004), irrespective of tagging location or handling treatment.ConclusionsFish tagged in the operculum musculature had comparable rates of mortality and tag loss to the current “best practice” standard of intraperitoneal tagging. We show that placement of PIT tags in operculum musculature is a viable alternative to placement in the peritoneal cavity.
Highlights
Passive integrated transponder (PIT) tags are commonly used to identify individual fish
Among the explanatory variables tested, only weight was an important determinant of probability of tag loss or mortality (Table 1)
Our results indicate that the operculum musculature is a viable alternative location for PIT tagging with comparable rates of tag loss and mortality to that of the widely utilized “best practice” of intraperitoneal PIT insertion
Summary
Passive integrated transponder (PIT) tags are commonly used to identify individual fish. Mortality rate and welfare scores between Atlantic salmon post-smolts (n = 798) marked with PIT tags either in the operculum musculature or the abdominal cavity (standard practice) before and after mechanical delousing. Because they are small (12–24 mm long), lightweight, durable and inexpensive, passive integrated transponder (PIT) tags are commonly used to identify individual fish) [13]. PIT tags are inserted into a fish’s abdominal cavity either via injection [1] or through a small incision along the ventral midline Both methods are quick and avoid the need for sutures [5]. Exploring alternative tag placement where the likelihood of loss and accidental human ingestion is minimized is necessary for this technology to be used in aquaculture research at commercial scale
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