1. The influences of fish physiology and habitat conditions on the retention rates of Pacific lamprey
carcasses in Upper Toppenish Creek, a small tributary stream in South Central Washington, USA.
Eva Carl1, Michelle George1, Ralph Lampman 2
1. Heritage University
2. Yakama Nation Fisheries Resource Management Program
Abstract: Numerous studies have assessed the importance of
spawned salmon carcasses for stream and riparian productivity;
very few studies have examined the roles played by spawned
Pacific lamprey (Entosphesnus tridentatus) carcasses. The
purpose of this study was to evaluate retention rates of adult
Pacific lamprey carcasses in a stream channel in relationship to
fish physiology (e.g. sex, sexual maturity, amount of eggs, size)
and habitat conditions (e.g. habitat type, water depth, location
along horizontal axis). A total of 25 carcasses (from a Yakama
Nation artificial propagation program) uniquely identified with floy
tags were released at equal intervals (2 m apart) in a 50 mreach
of Toppenish Creek (a tributary to lower Yakima River in south
central Washington, USA) at river km 59.9 on June 19, 2013.
Movements of these carcasses were monitored over a 24-day
period ending in July 13, 2013. Carcasses consisted of 10
males and 15 females, some of which were immature fish
lacking mature gametes while others were sexually mature with
varying amounts of eggs. The carcasses placed in the channel
margins remained in place at a higher rate in the short-term but
were detected less frequently in the long-term compared to
those placed in the middle of the channel, indicating potential
predation by mammalian species. Carcasses that remained in
channel tended to deposit in deep sections of the pools and pool
tailouts where fine sediment was more prevalent (typical habitat
for larval lamprey). Detection frequency was also higher for
male fish (vs. female), sexually mature fish (vs. immature), and
those with less eggs, suggesting that female fish with more eggs
and immature fresh migrants may be more preferred by
predators
Figure 1: Initial ration of Males to Females Figure 2: Female carcasses with amount of eggs
Discussion: The overall results showed that the
male fish were detected more often in the creeks than
the female fish. The female fish with fewer eggs were
also detected more than fish with eggs.
Figure 4: Overall detection ratio
Figure 3: How ripe were the females with eggs
Results:
References:
1. http://andrew.hedges.name/experiments/random/original.html
Methods: A 50m section of the creek was selected that had two types of
conditions, riffle and pool, that separated the creek site into three sections.
The riffle is mostly shallow water with large rocks and swift moving water; the
pool is deeper water with sand, mud and slower moving water. The 50m site
was measured into 2m sections where the lamprey carcasses would be
placed. Each section was divided into five areas from edge to edge of the
creek and given a number that was chose by a random number website
application1 so each placement would vary. There were 10 male and 15
female carcasses placed, some of the females still had eggs and some had
already spawned out. The site was visited every 3 days for 24 days to
measure movement of the carcasses downstream from the release spots.
The carcass that were used, we kept a log of information about each fish.
This is how we could detail the female fish with or without eggs and which
ones were detected more often.
Photo 1: Aerial photo of Toppenish Creek
Photo 2: Carcasses used in study Photo 3: Found a carcass in pooled area
Acknowledgements:
Michelle George
Ralph Lampman
Jessica Black
Nina Barcenas