Efforts to protect or rehabilitate depressed blue sucker Cycleptus elongatus populations require an understanding of life-history characteristics and reproductive biology to provide fisheries managers with the tools required for science-based management. The objective of this study was to examine the reproductive biology of blue sucker in the Wabash River, Indiana, during March and April 2006. A total of 105 reproductively mature blue sucker (53 males, 52 females) was collected using boat electrofishing to examine size-at-maturity, absolute fecundity, gonadosomatic index (GSI), relative fecundity, and estimated egg size. Size-at-maturity was estimated at 515 mm total length (TL) for males and 568 mm TL for females. Mean absolute fecundity of females captured during the study was 150 704 eggs per female (range, 26 829-267 471 eggs per female) and was positively related to both TL (r 2 = 0.66) and wet weight (r 2 = 0.77). Mean GSI was 6.4% (range, 2-9.3%) for males and 17.2% (range, 4.3-23.4%) for females. Relative fecundity ranged from 15 331 to 65 887 eggs kg )1 body weight (mean = 46 946 eggs kg )1 body weight) and was strongly correlated with GSI (r 2 = 0.87). Mean estimated egg size was 278 eggs g )1 (range, 229 364 eggs g )1 ) and exhibited an inverse relationship to GSI (r 2 = 0.42). The results of our study provide information on the reproductive biology of blue sucker which can be used to aid in the identification of potential recovery threats for depressed populations.
Blue sucker, Cycleptus elongatus (Lesueur), populations have declined because of habitat degradation and overharvest, and little information exists on the population characteristics and stock dynamics of this species. We examined size and age structure, mortality, growth and condition of blue sucker in the Wabash River, Indiana-Illinois, USA. A total of 356 fish collected by electric fishing from June 2003 to April 2006 ranged from 238 to 775 mm total length and 85 to 5288 g wet weight. Age ranged from 3 to 16 years and annual mortality ranged from 22 to 25%. Annual growth was greatest among younger age classes (range 48-141 mm yr )1 ) and declined after age 6, likely at the onset of reproductive maturity. Variation in the relative condition factor (range 66-141) was heteroscedastic over the size range of fish sampled, perhaps attributable to seasonal differences in reproductive condition among mature fish. K E Y W O R D S : age distribution, blue sucker, Cycleptus elongatus, growth, mortality, size structure. Present address: 105 110 J F A J J A O D M M S N Figure 6. Mean relative condition factor by month for blue sucker from the Wabash River, Indiana-Illinois. Error bars represent 95% confidence intervals about the mean condition. BLUE SUCKER IN THE WABASH RIVER 25
Numerous studies on smallmouth bass (Micropterus dolomieu) have focused on movements, diets, and capture rates among habitat types, but we are aware of no study that has documented capture rates and size structure by month to aid in assessment and management of this fish. The objective of this study was to determine monthly sampling dynamics and population size structure of smallmouth bass in four northeastern South Dakota glacial lakes. Smallmouth bass were collected monthly (May-September) from Enemy Swim Lake and Roy Lake in 2007 and Clear Lake and Pickerel Lake in 2008 using modified-fyke nets and night electrofishing in rocky habitats. Monthly mean catch-per-unit-effort (CPUE) values for smallmouth bass collected with fyke nets were variable but generally low (0.2-4.7 fish/net night) across months and lakes. Monthly mean CPUE values for smallmouth bass collected by electrofishing were variable in all four lakes (99.7-771.8 fish/h); however, in Clear Lake and Enemy Swim Lake CPUE significantly increased from May through September, primarily due to age-0 bass becoming vulnerable to electrofishing. For all lakes except Clear Lake, there were no significant differences in monthly mean CPUE values of 180 mm and longer smallmouth bass. Length distributions varied by month, but in general May and June samples contained a higher proportion of larger individuals than later sampling months. Overall mean relative weight (Wr) values were greater than 80, but relative weight varied among lakes and months. Our results suggest that spring (May to June) sampling of smallmouth bass using night electrofishing in rocky habitats will result in the broadest length range of captured bass.
We estimated the influence of predation by Smallmouth Bass Micropterus dolomieu on recruitment of age‐0 Yellow Perch Perca flavescens in two northeastern South Dakota glacial lakes. We estimated a likely range in consumption of age‐0 Yellow Perch using Smallmouth Bass diet information from two time periods when age‐0 Yellow Perch constituted high (2008) and low (2012 and 2013) proportions of Smallmouth Bass diets, and bass population size estimates as inputs in a bioenergetics model. The proportion of age‐0 Yellow Perch consumed by the Smallmouth Bass populations was determined by comparing estimates of consumption with estimates of age‐0 perch production. During 2008, age‐0 Yellow Perch constituted between 0% and 42% of Smallmouth Bass diets by weight, whereas during 2012 and 2013, age‐0 perch constituted between 0% and 20% of bass diets by weight. Across both lakes and time periods, production of age‐0 Yellow Perch ranged from 0.32 to 1.78 kg·ha−1·week−1. Estimates of Smallmouth Bass consumption measured during the same intervals ranged from 0.06 to 0.33 kg·ha−1·week−1, equating to consumption of between 1% and 34% of the available Yellow Perch biomass. Given current conditions relative to Smallmouth Bass abundance and consumption dynamics and production of age‐0 Yellow Perch, it does not appear that Smallmouth Bass predation acts as a singular factor limiting recruitment of age‐0 Yellow Perch in our study lakes. However, future research and management initiatives should recognize that the long‐term impact of Smallmouth Bass predation is not static and will likely fluctuate depending on environmental (e.g., temperature) and biotic (e.g., trends in macrophyte abundance, predator and prey population structure and abundance, and predatory fish assemblage dynamics) characteristics. Received December 19, 2014; accepted April 20, 2015
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