Summary
The increasing popularity of catch-and-release angling indicates a need to identify best practices that minimize sublethal injuries, impairments, and mortality. One factor impacting the viability of catch and release is the risk of hooking injury, which can impact survival in released fishes. In particular, deep hooking is known to increase post-release mortality in numerous species. As such, best practices include the use of equipment and promotion of angler behaviors that reduce incidences of deep hooking. In some areas, angling at night is restricted because of concerns that deep hooking is elevated relative to angling during the day. However, there has been little empirical research investigating whether deep hooking is influenced by the time of day (light levels). In the present study, we captured bluegill (Lepomis macrochirus Rafinesque, 1810) and pumpkinseed (Lepomis gibbosus Linnaeus, 1758) using active angling (cast and retrieve) and passive angling (with a bobber) throughout the 24-hr period, and recorded hook depth and hook location for each fish. We found that passive angling methods resulted in deeper hooking than active angling methods for both bluegill and pumpkinseed across all time periods. Although few pumpkinseed were caught at night, we found that the pumpkinseed caught were hooked more deeply and in more damaging hooking locations at night relative to the day. Hooking injury was independent of diel period for the more frequently landed species, bluegill. These findings emphasize the species-specific nature of catch-and-release outcomes, and suggest that further research is warranted to adequately quantify the impacts of recreational fishing at night.
Methodology
Field Site
Research was conducted at the Queen’s University Biology Station on Lake Opinicon, Ontario (44°33´55.37˝N, 76°19´23.26˝W). Lake Opinicon is a mesotrophic lake (i.e., has a typical clarity measured with a Secchi disc between 3–5 m), with a maximum depth of 11 m. Angling was conducted by the researchers in 4-hr blocks between April 30 and May 6, 2015. The entire 24-hr cycle was covered during this time period, with each light level category (dark, low light, bright light; see section below on data management and statistical analyses) represented on at least four separate occasions. Light levels were inferred by time period, with no additional measurements taken to assess light levels. The water temperature at the time of the experiment (measured at a depth of 0.8 m) ranged between 10 and 18 °C throughout the study, while air temperature ranged from 8 to 24 °C. Weather over the study period was mostly clear, with some periods of light cloud cover, and no precipitation. Moon phases during the study period ranged from waxing gibbous (April 30– May 2) to waning gibbous (May 4–May 6), with the full moon occurring on May 3 (Government of Canada 2016).
Experimental protocol
Bluegill and pumpkinseed were angled using rod and reel from a dock or fishing boat using small barbed J hooks (Mustad, Gjovik, Norway N-2801, baitholder style, size 8). All anglers used the same organic bait (small worm pieces), measured to 1 cm in length, and two split shots (Gremlin Green, White Bear Lake, MN, USA, 55110, tin sinkers, unleaded, removable) were placed 5–6 cm above the hook. Fishing took place using both active and passive angling methods, with passive angling involving the use of spring oval bobbers placed 0.8 m above the hook. Passive anglers were instructed to wait until the bobber moved to reel the line in, and the same bobber type was used throughout the 24-hr period, (i.e., no photoluminescent bobbers were used at night). Active anglers did not make use of bobbers, but casted and jigged the lure while reeling in. Anglers attempted to standardize angling effort between the two methods as evenly as possible across the 24-hr period and between the two methods.
On landing, the anatomical location of the hook was recorded as: upper lip, lower lip, corner of mouth, upper palate, distal pharynx or esophagus, or gill. No instances of hooking in the tongue were observed, and only one instance of hooking in another location occurred in the study (one fish was hooked in the eye). This event, and any 510 Bulletin of Marine Science. Vol 93, No 2. 2017 hook that penetrated the tissue of the distal pharynx, esophagus, or any part of the gill lamellae, were referred to as a “foul hooking event.” Hooking depth (mm) was measured from the outermost edge of the upper lip to the site of hook penetration. Finally, fish were measured in mm for both total length (TL, the length from the front of the lip to the end of the straightened caudal fin) and standard length (SL, the length from the front of the lip to the end of the caudal peduncle). On release, each fish was given a dorsal fin clip to ensure any recaptured fish were not included in further analysis.