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In the Sacramento-San Joaquin River Delta, California, tidal forces that reverse river flows increase the proportion of water and juvenile late fall-run Chinook salmon diverted into a network of channels that were constructed to support agriculture and human consumption. This area is known as the interior delta, and it has been associated with poor fish survival. Under the rationale that the fish will be diverted in proportion to the amount of water that is diverted, the Delta Cross Channel (DCC) has been prescriptively closed during the winter out-migration to reduce fish entrainment and mortality into the interior delta. The fish are thought to migrate mostly at night, and so daytime operation of the DCC may allow for water diversion that minimizes fish entrainment and mortality. To assess this, the DCC gate was experimentally opened and closed while we released 2983 of the fish with acoustic transmitters upstream of the DCC to monitor their arrival and entrainment into the DCC. We used logistic regression to model night-time arrival and entrainment probabilities with covariates that included the proportion of each diel period with upstream flow, flow, rate of change in flow and water temperature. The proportion of time with upstream flow was the most important driver of night-time arrival probability, yet river flow had the largest effect on fish entrainment into the DCC. Modelling results suggest opening the DCC during daytime while keeping the DCC closed during night-time may allow for water diversion that minimizes fish entrainment into the interior delta. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

ABSTRACT Anthropogenic alterations to river systems, such as irrigation and hydroelectric development, can negatively affect fish populations by reducing survival when fish are routed through potentially dangerous locations. Non-physical barriers using behavioural stimuli are one means of guiding fish away from such locations without obstructing water flow. In the Sacramento-San Joaquin River Delta, we evaluated a bio-acoustic fish fence (BAFF) composed of strobe lights, sound and a bubble curtain, which was intended to divert juvenile Chinook salmon ( Oncorhynchus tshawytscha) away from Georgiana Slough, a low-survival migration route that branches off the Sacramento River. To quantify fish response to the BAFF, we estimated individual entrainment probabilities from two-dimensional movement paths of juvenile salmon implanted with acoustic transmitters. Overall, 7.7% of the fish were entrained into Georgiana Slough when the BAFF was on, and 22.3% were entrained when the BAFF was off, but a number of other factors influenced the performance of the BAFF. The effectiveness of the BAFF declined with increasing river discharge, likely because increased water velocities reduced the ability of fish to avoid being swept across the BAFF into Georgiana Slough. The BAFF reduced entrainment probability by up to 40 percentage points near the critical streakline, which defined the streamwise division of flow vectors entering each channel. However, the effect of the BAFF declined moving in either direction away from the critical streakline. Our study shows how fish behaviour and the environment interacted to influence the performance of a non-physical behavioural barrier in an applied setting. Published 2012. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

ABSTRACT Research on rare and threatened species is often limited by access to sufficient individuals to acquire information needed to design appropriate conservation measures., Using a combination of data from pop-up archival transmitting (PAT) tags across multiple institutional programmes, movements and habitat use of endangered smalltooth sawfish, Pristis pectinata were determined for animals from southern Florida and the Bahamas., All P. pectinata (n = 12) generally remained in coastal waters within the region where they were initially tagged, travelling an average of 80.2 km from deployment to pop-up location. The shortest distance moved was 4.6 km and the greatest 279.1 km, averaging 1.4 km day-1. Seasonal movement rates for females were significantly different with the greatest movements in autumn and winter., Pristis pectinata spent the majority of their time at shallow depths (96% of their time at depths <10 m) and warm water temperatures (22-28°C)., Given sawfish show a degree of site fidelity punctuated by limited migratory movements emphasizes the need for conservation and management of existing coastal habitats throughout the species' range., Published 2013. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]