Changes in foraging and predator avoidance behavior of Japanese dace (Pseudaspius hakonensis) to predation risk by invasive smallmouth bass (Micropterus dolomieu) in a Japanese lake

Author(s):  
Miles I. Peterson ◽  
Satoshi Kitano
2009 ◽  
Vol 66 (2) ◽  
pp. 212-223 ◽  
Author(s):  
Scott D. Kaufman ◽  
Ed Snucins ◽  
John M. Gunn ◽  
Wayne Selinger

In lake trout ( Salvelinus namaycush ) lakes of northeastern Ontario, Canada, aerial surveys of fishing activity on individual lakes (N = 589) and quantitative gillnet surveys (N = 65) were used to assess the effects of road access on angling effort and the presence of introduced smallmouth bass ( Micropterus dolomieu ). Angling effort, particularly during the open-water season, was highest and often exceeded estimated sustainable levels on lakes with good road access. Approximately 25% of the remote lakes also received excessive pressure during the winter season. Angler numerical responses to lake trout abundance were detected in remote lakes, but not in road-accessible lakes. Smallmouth bass were more prevalent in lakes with road access and human settlement (either cottages or lodges), supporting the theory that they were introduced into these lakes. Lake trout populations were depleted throughout much of the study range. Even without road access or smallmouth bass, lake trout abundance was still 47% lower than in unexploited reference lakes. When bass and (or) road access were present, lake trout abundance decreased by 77%. Remote lake trout populations in this area are clearly vulnerable to the negative impacts of improved access, a vector for both overexploitation and species introductions.


2008 ◽  
Vol 122 (4) ◽  
pp. 303 ◽  
Author(s):  
Nathan M. Roberts ◽  
Charles F. Rabeni ◽  
John S. Stanovick ◽  
David A. Hamilton

The reintroduction of River Otters (Lontra canadensis) between 1982 and 1992 resulted in widespread occurrence of the species throughout the Missouri Ozarks. This study examined otter diets from the vicinity of two Ozark streams in relation to seasonal and spatial trends. Otter scats (N = 4750) were collected and analyzed from the Osage Fork River and Big Piney River during the summer and winter seasons of 2001 and 2002. During the winter (January-March), fish occurred in 86% of the samples. During the summer (June–August), occurrence of fish dropped to approximately 15% for both rivers. Seven families of fish were identified in the diets, with Centrarchidae being most common regardless of river or season. Within the Centrarchidae, the genus Lepomis (mostly Longear Sunfish, Lepomis megalotis) was most common, with Micropterus (mostly Smallmouth Bass, Micropterus dolomieu) and Rock Bass (Ambloplites rupestris) also well represented. The mean age of Ambloplites consumed (mean = 3.3 years) was consistently older than that of either Micropterus (mean = 2.54 years) or Lepomis (mean = 2.78 years). Crayfish were recovered from a mean of 85.2% of scats in the winter and 99% in the summer. Smaller fish and crayfish were more common from the upper reaches of the streams while larger fish were prevalent in the lower reaches.


<em>Abstract</em>.—We reviewed the published and gray literature associated with Neosho Smallmouth Bass <em>Micropterus dolomieu velox</em> and the genetically distinct Ouachita lineage. Substantial interstream variation appears to occur among these populations, particularly related to age. The Neosho subspecies is more abundant, grows faster, and lives longer than the genetically distinct Ouachita lineage. Recruitment is highly variable among streams for both populations and appears to be related to some undescribed aspects of hydrology but also likely reflect bias due to sampling gear. Information on annual and seasonal trends is lacking for the Neosho subspecies and the Ouachita lineages, particularly as related to the spawning period. Conservation efforts for these lineages might benefit from agencies partnering to achieve goals that extend beyond a particular agency’s responsibilities and state boundaries. Recognition of spatial and temporal considerations, combined with a better understanding of the population dynamics as related to abundance, growth, mortality and reproduction, would benefit the creation of more effective conservation and management strategies for genetically distinct populations of Smallmouth Bass <em>M. dolomieu</em>.


2015 ◽  
Vol 282 (1820) ◽  
pp. 20151886 ◽  
Author(s):  
Christine N. Bedore ◽  
Stephen M. Kajiura ◽  
Sönke Johnsen

Cephalopods, and in particular the cuttlefish Sepia officinalis , are common models for studies of camouflage and predator avoidance behaviour. Preventing detection by predators is especially important to this group of animals, most of which are soft-bodied, lack physical defences, and are subject to both visually and non-visually mediated detection. Here, we report a novel cryptic mechanism in S. officinalis in which bioelectric cues are reduced via a behavioural freeze response to a predator stimulus. The reduction of bioelectric fields created by the freeze-simulating stimulus resulted in a possible decrease in shark predation risk by reducing detectability. The freeze response may also facilitate other non-visual cryptic mechanisms to lower predation risk from a wide range of predator types.


2005 ◽  
Vol 62 (11) ◽  
pp. 2649-2660 ◽  
Author(s):  
Geoffrey B Steinhart ◽  
Nancy J Leonard ◽  
Roy A Stein ◽  
Elizabeth A Marschall

We studied how storms, angling, and nest predation during angling affected smallmouth bass (Micropterus dolomieu) nest survival in the Bass Islands, Lake Erie, Ohio, USA. Increasing angler effort and introduction of an exotic nest predator, round goby (Neogobious melanostomus), have raised concerns about smallmouth bass recruitment in Lake Erie. We surveyed smallmouth bass nests and calculated daily survival rates for nests assigned to different angling treatments: control, angling without predation, or angling with predation treatments. Only 30% of control nests were successful compared with 11% of angling without predation and 14% of angling with predation treatments. We used the Mayfield method and maximum likelihood models in the program MARK to estimate the survival rates for nests of different treatments and exposed to different numbers of storms. Although nest predators consumed about 35% of broods during angling, daily nest survival rates of both angling treatments were similar. Angling reduced nest survival compared with controls by approximately 5%. Storms reduced both nest success and daily survival. The best model predicting daily nest survival included the added effects of angling treatment and number of storms. Thus, whereas storms and angling affected smallmouth bass nest survival, nest predation during angling did not.


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