Managing adult hatchery summer steelhead for a recreational fishery with reduced hatchery and wild interactions

Hatcheries whose purpose is to provide for a recreational fishery must minimize impacts on wild fishes. Management to reduce hatchery and wild interactions is especially important on river systems that contain Endangered Species Act (ESA) listed species. I examined adult hatchery summer steelhead, Oncorhynchus mykiss, behavior, current management and a potential future management practice in a river with both introduced and ESA listed steelhead. I used radio telemetry to determine hatchery summer steelhead activity, behavior, and examine management tactics in the Clackamas River, Oregon. I evaluated the movement and distribution of radio-tagged fish between July 2007 through January 2008 using a combination of fixed and mobile radio-tracking. In addition, I used electromyogram (EMG) transmitters to record activity and behavior while the fish were holding in their natal river. An EMG-tagged fish was caught on hook and line during tracking and is the first known instance of estimated activity levels during capture. I evaluated the fish recycling program on the Clackamas River. Recycling involves the transport and release of adult steelhead back downstream following their collection at the hatchery to increase angler success. I estimated that up to 41% of recycled fish were caught in the recreational fishery. However, the majority of fish (44 -67%) were unaccounted for after release and may negatively affect wild populations. The Oregon Department of Fish and Wildlife is investigating the feasibility of sterilizing returning adult hatchery steelhead to reduce hatchery and wild interactions and increase recreational fishing opportunity. To evaluate the effect of sterilization on adult fish behavior, I gonadectomized and radio-tagged 40 hatchery summer steelhead and monitored their behavior and contribution to the fishery compared to sham-operated fish. Gonadectomized fish remained in the river, were distributed downstream of control fish, and were caught in the recreational fishery. Based on my results, I conclude that sterilization may be a useful technique to improve angler opportunity while minimizing the impact to wild fish. Behavior and activity of hatchery fish and their responses to management procedures should be closely monitored to better manage hatchery fisheries

26th Annual Computational Neuroscience Meeting (CNS*2017): Part 3 - Meeting Abstracts - Antwerp, Belgium. 15–20 July 2017

This work was produced as part of the activities of FAPESP Research,\ud Disseminations and Innovation Center for Neuromathematics (grant\ud 2013/07699-0, S. Paulo Research Foundation). NLK is supported by a\ud FAPESP postdoctoral fellowship (grant 2016/03855-5). ACR is partially\ud supported by a CNPq fellowship (grant 306251/2014-0)

Improved estimates of age, growth and reproduction for the regionally endemic Galapagos sailfin grouper Mycteroperca olfax (Jenyns, 1840)

The Galapagos Sailfin grouper, Mycteroperca olfax, locally known as bacalao and listed as vulnerable by the IUCN, is culturally, economically, and ecologically important to the Galapagos archipelago and its people. It is regionally endemic to the Eastern Tropical Pacific, and, while an important fishery resource that has shown substantial declines in recent years, to date no effective management regulations are in place to ensure the sustainability of the Galapagos fishery for this species. Previous estimates of longevity and size at maturity for bacalao are inconsistent with estimates for congeners, which brings into question the accuracy of prior estimates. We set out to assess the age, growth, and reproductive biology of bacalao in order to provide more accurate life history information to inform more effective fisheries management for this species. The oldest fish in our sample was 21 years old, which is 2–3 times greater than previously reported estimates of longevity. Parameter estimates for the von Bertalanffy growth function (k = 0.11, L∞ = 110 cm TL, and to = − 1.7 years) show bacalao to grow much slower and attain substantially larger asymptotic maximum length than previous studies. Mean size at maturity (as female) was estimated at 65.3 cm TL, corresponding to a mean age of 6.5 years. We found that sex ratios were extremely female biased (0.009 M:1F), with a large majority of the individuals in our experimental catch being immature (79%). Our results show that bacalao grow slower, live longer, and mature at a much larger size and greater age than previously thought, with very few mature males in the population. These findings have important implications for the fishery of this valuable species and provide the impetus for a long-overdue species management plan to ensure its long-term sustainability

The codevelopment of coastal fisheries monitoring methods to support local management

Small-scale fisheries across the globe provide critical food security, livelihoods, and human well-being, but are threatened by a combination of local and global stressors, including overexploitation, pollution, and climate change. Participatory approaches to management, especially those that incorporate local communities and customary knowledge can provide meaningful biological information that supports sustainable fisheries management and builds local adaptive capacity to changing ocean conditions. Through a collaboration between fishers, scientists, NGOs, and regulating agencies, we developed a low-cost, low-tech method to assess the seasonal spawning peaks, lunar spawning cycles, and size at maturity (L50) for key targeted reef fish, combining traditional knowledge and practice with modern scientific approaches, including gonadosomatic index (GSI) and histology. Two years of community-based monitoring resulted in data from 57 species and 15 families of reef and nearshore fishes (n = 2595), with detailed information for 10 species at 4 locations across the Hawaiian Islands. Comparisons between community-collected GSI data and scientifically (histologically) assessed spawning cycles and size at reproductive maturity produced similar results suggesting that these approaches can be applied in data-poor fisheries to assess spawning seasons and size at maturity (L50), both of which are critical needs for effective fisheries management. Semistructured surveys revealed a large body of local knowledge on spawning times and harvest practices based on allowing spawning to occur before harvesting and protecting small and large size classes, but little evidence that fishers understand temporal patterns of spawning. This suggests that monitoring methods that fill key gaps such as this and are congruent with these local knowledge systems and customary harvest practices may be key for local stewardship and adaptive management

Effects of Gear Restriction on the Abundance of Juvenile Fishes along Sandy Beaches in Hawai'i.

In 2007, due to growing concerns of declines in nearshore fisheries in Hawai'i, a ban on gillnets was implemented in designated areas around the island of O'ahu in the main Hawaiian Islands. Utilizing a 17 year time-series of juvenile fish abundance beginning prior to the implementation of the gillnet ban, we examined the effects of the ban on the abundance of juveniles of soft-bottom associated fish species. Using a Before-After-Control-Impact (BACI) sampling design, we compared the abundance of targeted fishery species in a bay where gillnet fishing was banned (Kailua, O'ahu), and an adjacent bay where fishing is still permitted (Waimānalo, O'ahu). Our results show that when multiple juvenile fish species were combined, abundance declined over time in both locations, but the pattern varied for each of the four species groups examined. Bonefishes were the only species group with a significant BACI effect, with higher abundance in Kailua in the period after the gillnet ban. This study addressed a need for scientific assessment of a fisheries regulation that is rarely possible due to lack of quality data before enactment of such restrictions. Thus, we developed a baseline status of juveniles of an important fishery species, and found effects of a fishery management regulation in Hawai'i

Data from: Effects of gear restriction on the abundance of juvenile fishes along sandy beaches in Hawai'i

In 2007, due to growing concerns of declines in nearshore fisheries in Hawai‘i, a ban on gillnets was implemented in designated areas around the island of O‘ahu in the main Hawaiian Islands. Utilizing a 17 year time-series of juvenile fish abundance beginning prior to the implementation of the gillnet ban, we examined the effects of the ban on the abundance of juveniles of soft-bottom associated fish species. Using a Before-After-Control-Impact (BACI) sampling design, we compared the abundance of targeted fishery species in a bay where gillnet fishing was banned (Kailua, O‘ahu), and an adjacent bay where fishing is still permitted (Waimānalo, O‘ahu). Our results show that when multiple juvenile fish species were combined, abundance declined over time in both locations, but the pattern varied for each of the four species groups examined. Bonefishes were the only species group with a significant BACI effect, with higher abundance in Kailua in the period after the gillnet ban. This study addressed a need for scientific assessment of a fisheries regulation that is rarely possible due to lack of quality data before enactment of such restrictions. Thus, we developed a baseline status of juveniles of an important fishery species, and found effects of a fishery management regulation in Hawai‘i

beach_seine_BACI

beach_seine_BACI.csv is a comma-separated file containing data from beach seine surveys of juvenile fish populations from two sites on windward side of Oahu, Hawai

Results of general linear mixed models of catch per unit effort (CPUE) for (A) jacks, (B) bonefishes, (C) flagtails, and (D) Pacific threadfin following a Before-After-Control-Impact (BACI) design to measure differences in juvenile fish populations between a protected area (Kailua) and an unprotected area (Waimānalo), before and after a gillnet closure in Hawai‘i (error bars ± 1 SE).

<p>Results of general linear mixed models of catch per unit effort (CPUE) for (A) jacks, (B) bonefishes, (C) flagtails, and (D) Pacific threadfin following a Before-After-Control-Impact (BACI) design to measure differences in juvenile fish populations between a protected area (Kailua) and an unprotected area (Waimānalo), before and after a gillnet closure in Hawai‘i (error bars ± 1 SE).</p

Map of study area showing gillnet prohibited area (hatched area) in Kailua Bay and open area in Waimanalo Bay (A) on the island of O‘ahu in Hawai‘i (B).

<p>Red circles show sampling locations, and depth contours are colored from light (shallow) to dark (deep).</p

Commercial landings of bonefishes from 1900, and 1965–2011 for the island of O‘ahu.

<p>Vertical line represents gillnet ban in Kailua in 2007. Data from 1903 from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0155221#pone.0155221.ref055" target="_blank">55</a>], and otherwise from Hawai‘i Division of Aquatic Resources.</p