Multiple metrics provide context for the distribution of a highly mobile fish predator, the blue catfish

Abstract

Data sets with increased spatial and temporal resolution can help researchers and resource managers quantify representative distributional patterns of mobile sportfish. In this research, first, we illustrate patterns of sportfish distribution using individual (percent of population, residence time, number of movements) and combined distributional metrics. Second, we apply these metrics to one highly mobile fish species, the blue catfish (Ictalurus furcatus), across a range of spatial (whole reservoir, region, site) and temporal (year, month, diel period) scales. Specifically, we tracked 123 acoustically tagged blue catfish with a 20‐receiver array in Milford Reservoir, KS, USA. When we integrated metrics, four site‐specific distributional patterns emerged: (a) a large, active multi‐site fish aggregation, (b) localised site fidelity, (c) transitional sites and (d) rarely used locations. These patterns would not have been detected using a single metric as each measurement revealed a different piece of the distribution story. For example, if we had only quantified percent of population, we could identify fish location, but not whether individual fish spent time at a location or were just passing through. Our examination of multiple scales also provided a novel context for interpreting site‐specific patterns. As an illustration of this insight, using conventional approaches, we would have observed heterogeneity, but we would not have detected fish aggregations, in which individual fish either remained or repeatedly returned to a site. In summary, our results show the advantage of setting the entire ecosystem as the study boundary to integrate multiple responses using a spatially and temporally extensive data set.

Environmental Variation and Habitat Use Affect Blue Catfish Low‐Frequency Electrofishing Catch Rates

“…This result may be attributable to the fact that Blue Catfish are not usually dispersed evenly, instead schooling in discrete locations (Gerber et al. 2018). Alternatively, it is possible that as a relatively wide and shallow reservoir, Lake Dardanelle does not exhibit a depth range broad enough for variable depth effects to be significant.…”

Use of Angling Gear to Evaluate the Potential Benefits of Minimum Length Limits on a Highly Mobile Midwestern Blue Catfish Population

“…2011; Gerber et al. 2019), and frequently they were recaptured far from where they were tagged. Most fish were captured by anglers in the North Fork arm, indicating that fish, anglers, or both were concentrated in that arm.…”

“…2011; Gerber et al. 2019), they may not stay in the area where they were tagged and instead may be captured by anglers some distance away from their release site. This is especially relevant in a heterogenous system, such as a large reservoir with multiple tributary arms.…”

Merging Scientific Silos: Integrating Specialized Approaches for Thinking about and Using Spatial Data That Can Provide New Directions for Persistent Fisheries Problems

“…The geographic boundary of these fish was the longitudinal extent of the 66‐km 2 reservoir, as shown by reservoir‐wide detections (Figure 3C) and individual fish trajectories that covered the whole system (Figure 3D). In a clustered spatial framework, more mobile Blue Catfish frequented receivers in the middle reservoir region (Figure 3C; Gerber et al 2019). In our third example, we examined adult anadromous Alewives that were returning from the ocean to spawn ( n = 21 fish; April–May, 2007; Ipswich River, Massachusetts).…”

“…(E) Alewives could only move past the second barrier during high flows (8 of 21 upstream migrants passed the second barrier in 2007). Methods and related trends are described in Taylor et al (2019), Gerber et al (2019), and Frank et al (2011).…”