Fin condition was examined in 100–500 g hatchery-reared rainbow trout sampled in a large range of environmental conditions of an experimental farm. A method that is simple to use, requires little training, and does not need costly sophisticated equipment or reference to a model is proposed to assess fin erosion (defined as a decrease in size and profile alteration of fins). A procedure to reliably measure the length of the longest ray present in two selected fins (dorsal and pectoral) is described. Fin general profile is assessed using five levels of erosion based on the precise rank of intact or eroded rays to limit subjective bias. The suitability of the two descriptors of fin erosion under laboratory, farm or field conditions is discussed.

This study performed in the Patapédia River (Québec, Gaspésie) was designed to examine the space utilization and mobility patterns of individual Atlantic salmon parr over short time scales with frequent detections of position. In August 2004, n = 7 radio-tagged Atlantic salmon parr were located every 20 min during 10 tracking periods chosen to take into account the dawn, day, dusk and night periods. Parr showed important inter individual variability in space utilization and mobility patterns, occupying large home ranges (123 to 5602 m2) and sometimes migrating 2 km upstream in the river. No differences were observed in the mean distance travelled among the four daily periods by individual fish, but the estimated home ranges utilized during the four daily periods overlapped only partially, demonstrating that parr partly occupy different areas of the river during different parts of the daily cycle. The results suggest that an intense survey on a small number of fish may contribute to a complementary comprehension of space utilization and mobility patterns of Atlantic salmon parr when viewed in association with results from studies surveying larger number of fish at lower frequency.

A microcontrolled fish tag which records post-tagging life span, was developed and tested as a prototype. The method of making the tag and the results of tank test trials on chinook salmon (Oncorhynchus tshawytscha) and field trials on chum salmon (Oncorhynchus keta) are presented. This tag was specifically designed to measure survey life (SL) but may have other applications. Survey life is an essential component for area-under-the-curve (AUC) estimation of Pacific salmon (Oncorhynchus spp.) spawning escapements. Accurate escapement estimates are critically important for salmon fisheries management and science. However, AUC spawner estimates must often employ average SL values from historic rather than year-specific studies because direct estimates of SL can require extensive and costly tag-recapture programs. Using assumed SL values can introduce serious bias in population estimates, therefore alternative methods of determining annual SL are important. In this study, the new tag estimated SL by measuring the elapsed time from tagging until the fish came to rest permanently on its lateral or dorsal surface. Details on how to construct the tag are provided so that researchers will be able to make their own.