Advances in Salish Sea Acoustic Telemetry: 2015 Array Deployments and Promising Transmitter Performance

The first fish tracking arrays were deployed in the Salish Sea over a decade ago. These arrays have yielded a rich data set which have provided the first direct estimates of early marine-survival and migratory behavior for acoustic-tagged juvenile sockeye, Chinook, Coho and steelhead \u3e130 mm in fork length (FL). In spring of 2015, as part of the Salish Sea Marine Survival Project, the Pacific Salmon Foundation, the Ocean Tracking Network and Kintama Research deployed additional arrays in the Discovery Islands and Johnstone Strait (north of the Strait of Georgia) to provide higher resolution survival data. These new arrays use receivers that can detect VEMCO acoustic tags that transmit at 69 kHz, as well as new, smaller tags that transmit at 180 kHz. These new tags can be implanted into smaller salmon smolts (\u3e100 mm FL), but the disadvantage is reduced detection range and battery life. When designing the array, we considered the tradeoffs between detection efficiency, survival estimation, array design, and costs, and then tested the performance of the smaller tag by double-tagging 50 steelhead smolts with both tag types. We used high powered 69 kHz V9 tags to estimate presence because these tags have had excellent detection efficiency in past studies. The smaller 180 kHz V4 tag programming emulated the programming typically used to track small salmon smolts through the SOG. To estimate the detection efficiency of the smaller tag, we compared the number of 180 kHz ID codes to the number of 69 kHz ID codes detected on each array. The resulting detection efficiency of the V4 tag on the Discovery Islands sub-array was 74% (SE=0.10). Thus for the many salmon populations that migrate north through the Salish Sea (e.g. many Fraser River populations), it is now possible to estimate early-marine survival over a wider range of smolts sizes

Survival of Migrating Salmon Smolts in Large Rivers With and Without Dams

The mortality of salmon smolts during their migration out of freshwater and into the ocean has been difficult to measure. In the Columbia River, which has an extensive network of hydroelectric dams, the decline in abundance of adult salmon returning from the ocean since the late 1970s has been ascribed in large measure to the presence of the dams, although the completion of the hydropower system occurred at the same time as large-scale shifts in ocean climate, as measured by climate indices such as the Pacific Decadal Oscillation. We measured the survival of salmon smolts during their migration to sea using elements of the large-scale acoustic telemetry system, the Pacific Ocean Shelf Tracking (POST) array. Survival measurements using acoustic tags were comparable to those obtained independently using the Passive Integrated Transponder (PIT) tag system, which is operational at Columbia and Snake River dams. Because the technology underlying the POST array works in both freshwater and the ocean, it is therefore possible to extend the measurement of survival to large rivers lacking dams, such as the Fraser, and to also extend the measurement of survival to the lower Columbia River and estuary, where there are no dams. Of particular note, survival during the downstream migration of at least some endangered Columbia and Snake River Chinook and steelhead stocks appears to be as high or higher than that of the same species migrating out of the Fraser River in Canada, which lacks dams. Equally surprising, smolt survival during migration through the hydrosystem, when scaled by either the time or distance migrated, is higher than in the lower Columbia River and estuary where dams are absent. Our results raise important questions regarding the factors that are preventing the recovery of salmon stocks in the Columbia and the future health of stocks in the Fraser River

Home site fidelity in Black Rockfish, Sebastes melanops, reintroduced into a fjord environment

Between December 2004 and January 2007, we studied the movements of six Black Rockfish (Sebastes melanops) that had been fitted with acoustic transmitters and reintroduced into a fjord environment at the edge of Vancouver Harbour, British Columbia. The Black Rockfish were released in December 2004 and April 2005 at a reef characterized by complex rocky structures and steep slopes; bottom depths at the site dropped from 10 to 55 m within a horizontal distance of only 30 m. The reef, however, is small (approximately 4500 m2) and is surrounded by soft bottom habitats used infrequently by Black Rockfish. VEMCO VR2 receivers were deployed at the release site and at outlying reefs located 1 and 4 km away. Acoustic data suggest that one individual emigrated from the reef after 11 months of residency and a second individual disappeared abruptly after 6 weeks on the reef, possibly due to fishing mortality or emigration. The four remaining individuals appear to have confined their movements to the release site, using an area 6 to 10 times smaller than the home ranges reported for populations in low-gradient coastlines in California and Oregon

Session C3: Balancing Ocean and Freshwater Survival Rates When Managing Anadromous Fish Passage

Abstract: Salmon conservation efforts typically assume that expediting smolt movements into the ocean to mimic historic flow conditions will improve overall survival in dammed river systems. Management agencies are therefore encouraged to reduce the duration of the freshwater migration phase by increasing migration rates using approaches such as increasing spill, transport, or reservoir drawdown and, in extreme cases, dam breaching. Telemetry results for Snake River Spring Chinook smolts in the Columbia River (western North America) allow us to compare survival rates in four successive habitats in 2006-08: Hydropower system (8 dams), Estuary, River Plume, and Coastal Ocean. Relative to the Hydrosystem, daily survival rates were usually lowest in the Estuary and Plume, while Coastal Ocean survival rates were slightly lower than the Hydrosystem. Critically, marine survival rates never exceeded hydrosystem survival rates. It is also possible to compare the survival rates of various species of acoustically tagged salmon reaching the mouth of the Columbia River with those making a similar migration down the undammed Fraser River in Canada. We will compare these survival values and show how they are similar and where they are different. Overall, because management actions reducing freshwater residence time increase saltwater residence time by equivalent amounts, accelerating the movement of smolts out of the hydrosystem may be counterproductive and be economically costly, because such actions may simply change the location where smolts die, not improve survival as intended. Whether a chosen hydrosystem action actually enhances salmon conservation thus depends upon whether ocean survival rates are higher or lower than in freshwater. Using the data collected over the past decade using rigorously designed telemetry systems, my company has been able to develop a useful database of comparative survival rates demonstrating that there may be significant opportunity to increase both salmon conservation and power generation in years of poor ocean conditions by slowing freshwater migration rates, because a net survival benefit may accrue from remaining in freshwater for longer periods. Simply put, freshwater losses may be lower than those experienced in the ocean

CH_RMark Chilko sockeye survival

This file contains the capture histories (CH), or technically the detection histories, for acoustic tagged Chilko Lake sockeye. This file is called by the accompanying R script to produce survival and detection probabilities

RMark Survival Estimation for Chilko 2012

This file contains the R script used to estimate survival of Chilko Lake sockeye smolts with a Cormack-Jolly-Seber model using Program MARK via RMark

VCV matrix

This file contains the Chilko Lake sockeye CJS variance-covariance estimates which are used to calculate the variance on cumulative survival estimates. This file is called by the accompanying delta method R script

Delta_Method_for_Chilko2012

This file contains the R script used to estimate the variance on the Chilko sockeye cumulative survival estimates using the delta method