Effect of visible implant elastomers (VIE) and coded wire tags (CWT) on the growth, survival, and tag retention of juvenile European whitefish (Coregonus lavaretus)

This study examined the effect of visual implant elastomers (VIE) and coded wire tags (CWT) on the growth, survival, and tag retention of juvenile European whitefish, Coregonus lavaretus (L.), (mean body weight 18.7 ± 0.4 g, mean body length 9.7 ± 0.4 cm). The VIE tags were implanted subcutaneously in the anterior head, and the CWTs were implanted intramuscularly under the left gill operculum. The experiment consisted of two stages. The first stage (70 days) examined the effects of tagging on growth and survival, while the second stage (days 71-140) focused on assessing tag retention. Daily and specific growth rates, feed conversion factor, condition factor, coefficient of body weight variation, and survival did not differ significantly between the control fish and those tagged with the VIE tags and CWTs. Tag retention was high in the fish tagged with both VIE tags (100%) and CWTs (93%).

Growth and Movements of Mummichogs (Fundulus heteroclitus) Along Armored and Vegetated Estuarine Shorelines

Alteration of estuarine shorelines associated with increased urbanization can significantly impact biota and food webs. This study determined the impact of shoreline alteration on growth and movement of the estuarine fish Fundulus heteroclitus in a tributary of the Delaware Coastal Bays. Fundulus heteroclitus is abundant along the east coast of the USA, and is an important trophic link between marsh and subtidal estuary. The restricted home range of F. heteroclitus allowed discrete sampling, and fish growth comparisons, along 35–65-m long stretches of fringing Spartina alterniflora and Phragmites australis marsh, riprap, and bulkhead. Fundulus heteroclitus were tagged with decimal Coded Wire Tags. Of 725 tagged F. heteroclitus, 89 were recaptured 30–63 days later. Mean growth rate (0.06–0.15 mm day−1 across all shoreline types) was greatest at riprap, lowest at Spartina and Phragmites, and intermediate at bulkhead, where growth was not significantly different from any other shoreline. This suggests that discernible environments exist along different shoreline types, even at the scale of tens of meters. No difference in movement distance was detected at different shoreline types; most individuals displayed a high degree of site fidelity. Forty-seven percent were recaptured within 5 m of their tagging location, although alongshore movements up to 475 m were recorded. Estimates of relative F. heteroclitus productivity, using relative density data from a concurrent study, were highest along Spartina and Phragmites, intermediate at riprap, and lowest at bulkhead. Therefore, despite greater growth rates along riprap than at vegetated shores, armoring reduces abundance sufficiently to negatively impact localized productivity of F. heteroclitus.

Preliminary evaluation of the effectiveness of visible implant elastomer and coded wire tags for tagging young-of-the-year Atlantic sturgeon, Acipenser oxyrinchus

The aim of the study was to determine the retention rates of visible implant elastomer (VIE) and coded wire tags (CWT) and the impact tagging had on the growth of Atlantic sturgeon, Acipenser oxyrinchus Mitchill, during an eight-week rearing period under laboratory conditions. Two size groups of young-of-the-year (YOY) sturgeon were used in the study. The tagging was not found to have a significant impact on the final total length or body weight or the condition coefficient of the sturgeon from either size group. Sturgeon survival in the different groups ranged from 90.6 to 100%. Mortality was not noted until two (CWT) and four (VIE) weeks following tagging and was probably not linked to tagging. The retention rate for VIE tags implanted in the rostrum in both size groups was 100%, while for tags implanted at the base of the pectoral fin was 93.5%. The retention of CWT in the smaller fish was 90%, and in the larger sturgeon it was 100%. Tagging small sturgeon with CWT and VIE is minimally invasive, and it did not impact the growth or condition of the tagged fish.

Evaluating the use of coded-wire tags in individually marking Odonata larvae

We tested a potential new tool for marking Odonata larvae internally, evaluating the retention rates of injected coded-wire tags (CWT) and the effects of these tags on larval performance. Two species of dragonfly larvae (Epitheca canis McLachlan (Odonata: Corduliidae) and Leucorrhinia intacta Hagen (Odonata: Libellulidae)) were injected with CWT. Tag loss rates were assayed over experimental periods of 22 and 60 days, respectively for the two species. To assess whether tagging had negative effects on larvae, mortality, and growth of tagged larvae were compared to untagged larvae held in the same conditions. Tag retention rates were high (92–100%) and CWT were easily retrieved from preserved larvae via dissection, permitting most tagged larvae to be individually identified. There was 100% survival in larvae injected with CWT and tags do not appear to impair growth. The high retention and retrieval rates of this marking approach combined with no increase in mortality associated with tagging suggest that CWT are a useful means of individually labelling a large number of Odonata larvae in a time-efficient manner.

Coded wire tagging of juvenile curimbatá, Prochilodus lineatus (Valenciennes, 1837) (Characiformes): mortality, tag retention, and growth

In recent decades, Brazilian hydroelectric reservoirs have been stocked with hundreds of millions of juvenile migratory fish, but almost no research on stocking has been conducted. In order to study stocking it is essential to tag the fish to be stocked. In this investigation we determined handling-induced mortality, tag retention rate, and absolute growth rate of hatchery-reared juvenile curimbatá (Prochilodus lineatus) tagged with coded wire tags (CWT), a tag widely used on stocked fish. We injected CWT into the dorsal musculature just below the first dorsal fin ray. Despite the need for frequent tag injector maintenance, this tagging location proved to be suitable for tagging juvenile curimbatá. We found no short-term mortality of juvenile curimbatá handled for CWT tagging, high retention rate for CWT (≥ 98.2%) even after 174 d of tagging, and no influence on absolute growth rate by CWT. We conclude that CWT is effective at tagging juvenile curimbatá, and we expect that it will also be effective for many other Brazilian fish species used for stocking.