Monitoring the spawning behaviour of chum salmon with an acceleration data logger

Abstract

– The continuous observation of salmon behaviour in some wild environments can be extremely difficult. We recorded spawning behaviour of female chum salmon (Oncorhynchus keta) in the field simultaneously using visual observation and fish‐borne data loggers with two‐axis accelerometer sensors. Using only acceleration records, behaviours were successfully classified into the eight well‐known components of spawning behaviour: swimming, nosing, exploratory digging, nest digging, probing, oviposition, covering and post‐spawning digging. To understand how the female chum salmon modulates spawning behaviours in relation to changes in environmental conditions, we compared the behaviours of salmon during normal flow of clear water to those of salmon during the heavy flow of turbid water after a storm. Salmon in the normal flow showed all eight behaviours, whereas salmon in the heavy flow showed only three behaviours: swimming, nosing and exploratory digging. The proportion of time spent on swimming was greater in the heavy flow than in the normal flow (mean of 98.47% vs. 92.84%). Moreover, the proportion of tail beating in swimming was greater in the heavy flow (77.86%) than in the normal flow (15.63%). Our results indicate that the behaviour of female chum salmon was strongly affected by the heavy flow of turbid water after a storm. The recording of accelerations is a promising method for clarifying the spawning behaviour of salmonids in the wild where continuous visual observation is too difficult.

Quantifying the Behavioral Response of Spawning Chum Salmon to Elevated Discharges from Bonneville Dam, Columbia River : Annual Report 2005-2006.

“…These results agree with those of Tsuda et al (2006) who found a similar decrease in typical chum salmon spawning behaviors and a complete cessation of nest digging during a high discharge event. In that study, flows increased water depths by 80 cm, but the authors were unable to measure accompanying velocities.…”

“…The increase in swimming activity (i.e., tailbeat frequency) we observed at higher velocities suggests that chum salmon were incurring greater energetic costs to maintain position on their redds. Similarly, Tsuda et al (2006) found a substantial increase in tailbeat frequency of spawning chum salmon when flows were high in a Japanese river, and speculated that significant depletion of energy reserves may occur under such conditions. The three female chum salmon that left their redds when velocities exceeded 1 m/s may have done so to reduce energy expenditure.…”

“…This may be particularly true as the duration of delay increases. In the Tsuda et al (2006) study, fish spent more than a week in high discharges without spawning. However in our relatively short-duration tests, the changes we observed in digging frequency and hence the time it took to complete a redd probably did not affect chum salmon spawning success.…”

“…If chum salmon use all their available energy to hold position either on, or away from, their redds at elevated tailwaters, they may not complete spawning before they die. Furthermore, Tsuda et al (2006) speculated that spawning delay caused by elevated discharges may result in lack of oviposition (Barlaup et al 1994) or reduced egg viability of over-ripe eggs (DeGaudemar and Beall 1998). This may be particularly true as the duration of delay increases.…”

Correlations of metabolic rate and body acceleration in three species of coastal sharks under contrasting temperature regimes

“…Specific behaviours can be readily identified from acceleration data collected from free-ranging fish without direct observation (e.g. Tsuda et al, 2006;Whitney et al, 2010Whitney et al, , 2012Gleiss et al, 2013;Broell et al, 2013). These behaviours can then be paired with metabolic rate estimates through ODBA, allowing the construction of high-resolution time-energy budgets for free-ranging fish.…”