The phenology of critical biological events in aquatic ecosystems is rapidly shifting due to climate change. Growing variability in phenological cues can increase the likelihood of trophic mismatches (i.e., mismatches in the timing of peak prey and predator abundances), causing recruitment failures in important fisheries. We assessed changes in the spawning phenology of walleye (Sander vitreus) in 194 Midwest US lakes to investigate factors influencing walleye phenological responses to climate change and associated climate variability, including ice-off timing, lake physical characteristics, and population stocking history. Ice-off phenology shifted earlier, about three times faster than walleye spawning phenology over time. Spawning phenology deviations from historic averages increased in magnitude over time, and large deviations were associated with poor offspring survival. Our results foreshadow the risks of increasingly frequent natural recruitment failures due to mismatches between historically tightly coupled spawning and ice-off phenology.

Aim The aim of this chapter is to introduce and describe the importance of inland fisheries within a management context. Key contributions of inland fisheries to a diverse array of livelihoods services are highlighted, with emphasis on how globally widespread they are. Specifically, inland fisheries are identified as an important source of protein and livelihoods, especially for poor and developing nations, but also more globally and for recreational fisheries. Case studies are used to outline a number of challenges for maintaining inland fisheries livelihoods. Finally, opportunities for sustainable management of exploitation are described with the aim of stressing the resulting benefits to society. Main concepts covered The limited entry demands and ease with which people can access inland fisheries make them an extremely attractive livelihood option for subsistence and recreational fishers, and large-scale commercial operations, alike. Not only do they support fishers and those directly associated with the fishery but also a diverse value-chain and a growing tourist industry. Inland fisheries exploitation is high and becoming more widespread. Threats from development and ever-increasing populations have led some to suggest that inland fisheries livelihoods cannot be sustained. Challenges with estimating the amount of fish available, understanding diverse life-history patterns that determine how easily and frequently the population will recover from exploitation, and the high accessibility that makes it hard to track the quantity of fish being removed combine to make sustainable management difficult. There are, however, many people across the globe working to improve management and sustainability. From local fishers to national governments, diverse communities across the globe have recognized the need for change in order to sustain important inland fisheries livelihoods in the future. Main methods Cases studies emphasizing the importance of inland fisheries to people around the globe are used to demonstrate the diversity and extent of inland fisheries livelihoods. Conclusions Challenges associated with exploiting fishery resources sustainably are numerous. Using a series of case studies to illustrate how livelihoods across the globe are similar but at the same time different, the chapter describes how with careful and considered management and self-regulated exploitation this important livelihood can be sustained.

Ojibwe Tribes' approach to the natural world is guided by the original treaties between beings (species and spirits) and the Ojibwe people who reside in lands now known as the United States and Canada. Relationships with these beings, such as ogaa (walleye Stizostedion vitreus), are best characterised as taking care of a relative/gift for the next seven generations of Ojibwe. Initial denial of treaty rights by the state government has strongly influenced tribes' relationship with their relatives for over 100 years. Ogaa stocks and natural reproduction have declined in the Minocqua Chain of Lakes (Wisconsin, USA) over the last 20 years. Region-wide declines in ogaa have been attributed to many stressors such as overharvest by state-licensed anglers, invasive species and climate change. Here, we retroactively applied the resist-accept-direct (RAD) framework to the process used to create an interjurisdictional rehabilitation plan for the Minocqua Chain of Lakes. Specifically, we cover the following: progress to date on the rehabilitation plan; subsistence, cultural and spiritual challenges associated with resisting ecosystem change; unforeseen obstacles to rehabilitation; re-evaluation of the relationship with ogaa; unknowns; and contingency plans from a tribal perspective. Lastly, we discuss how the RAD framework could become more useful to tribes in the region.

Knowledge of density-dependent responses of fish populations to exploitation is important for the sustainable management of fisheries and in structuring fish populations to meet angler desires. To better understand the density-dependent responses of Walleye Sander vitreus to exploitation, we conducted a 10-year, 50% annual exploitation experiment on Sherman Lake, Wisconsin, during 2007-2016. In the following order, annual exploitation goals were met through liberalized recreational angling regulations, tribal spearfishing, and physical removals (if necessary). Response variables included total and sex-specific adult density, age-0 and age-1 relative abundance, age-0 to age-1 survival, length at maturity, individual growth, and population size structure. To control for environmental and interannual influences on adult density and recruitment, unexploited Escanaba Lake, Wisconsin, was used as a reference system. Total and sex-specific adult density and age-0 relative abundance did not differ between Sherman and Escanaba lakes. Age-1 relative abundance was significantly higher and more variable under elevated exploitation compared with the reference lake. Age-0 to age-1 survival significantly increased between pretreatment and elevated-exploitation time periods. Sex-specific length at maturity significantly declined between pretreatment and elevated-exploitation time periods. Mean juvenile length at age increased, male asymptotic length declined, and the proportional size distribution of quality-sized Walleye declined between pretreatment and elevated-exploitation time periods. Our results suggest that compensatory age-0 to age-1 survival and declines in length at maturity interacted to offset elevated-exploitation effects on adult density. Likewise, density-dependent growth responses were most evident in juveniles. Although the Sherman Lake Walleye population appeared resilient to elevated exploitation, we caution that this level of long-term exploitation is likely not sustainable for most Walleye populations due to the findings of previous exploitation studies and observations of depensatory recruitment dynamics in Walleye.

There is a fundamental conflict between harvesting fish and conserving their biomass. Managers mediate this conflict with regulations that control fishery methods and amounts of harvest. In most recreational fisheries, aside from closed seasons, the precise control of fishing effort is difficult to achieve because fisher entry into a managed area is often unlimited and because effort can be influenced by both direct and indirect factors. Choosing the best fishing regulations is also complicated by a need to jointly regulate and accommodate the desires of different user groups who share the fishery. Regulations may need to account for (1) low-consumptive uses of fish populations that occur from catch-and-release fishing by recreational anglers and/or (2) both tribal subsistence and commercial fishers. We applied a suite of graphical techniques to data on a shared fishery, that for Walleye Sander vitreus in Mille Lacs Lake, Minnesota, to examine the trade-offs between fishery yield and spawner biomass on a per-recruit basis across a range of harvest tactics, so that fisheries managers could simultaneously evaluate a variety of regulations. We also used Bluegill Lepomis macrochirus data from several Minnesota lakes to further evaluate the utility of our approach. Some regulations were uniformly better than others because they provided higher yield for a given spawning biomass, and higher spawning biomass for a given yield at equilibrium, under a range of plausible levels of fishing effort. For a given level of fishing effort, we were able to identify a frontier in the yield-biomass space whereby an increase in either the yield or the biomass could only be achieved by a reduction in the other. In the absence of density-dependent changes to growth, maturity, or mortality, regulations that included a minimum length produced more optimal yield and spawner biomass than those that did not include a minimum length. We reduced the daunting task of choosing from dozens of regulations by considering just a few graphs that best demonstrated the trade-offs offered by a suite of regulations.

Fisheries can be managed based on surplus production models when only catch and effort data are available. However, reported catch and effort may not equal the true values. We studied the effects of jointly underestimated catch and effort on surplus production model parameter estimates (e.g., MSY, B-msy and F-msy) as well as estimates of key ratios (e.g., F/F-msy). We used ASPIC to examine various scenarios of underreporting for three example fisheries, North Atlantic swordfish, northern pike in Minnesota and queen conch in the Turks and Caicos Islands. With constant underestimation of catch and effort throughout time, MSY, B-msy and B-next are all underestimated by the same percentage, while F-last and the ratios, F/F-msy and B/B-msy, are not affected. As a result, harvest regulations can be set based on fishing mortality and the ratios. That is, when one thinks the harvest is MSY with F=F-msy, one is achieving MSY and F-msy even though the catch is actually larger than it is thought to be. However, increasing or decreasing trends in underreporting of catch and effort over time lead to errors in the parameter and ratio estimates whose direction is case-specific and whose magnitude can be high or low. Each fishery model responded differently to the simulated scenarios, which may be a result of different exploitation histories or the quality of the fit of the production model to the data. The wide range of outcomes observed may be due to the fact that underestimation of catch and effort can lead to a gain or reduction in data contrast. Simulations of a variety of possible scenarios similar to the methods in this study should be conducted if catch and effort are believed to be underestimated to determine how the surplus production model responds. (C) 2016 Elsevier B.V. All rights reserved.

The growth potential of Muskellunge Esox masquinongy was evaluated by back-calculating growth histories from cleithra removed from 305 fish collected during 1995-2011 to determine whether it was consistent with trophy management goals in northern Wisconsin. Female Muskellunge had a larger mean asymptotic length (49.8 in) than did males (43.4 in). Minimum ultimate size of female Muskellunge (45.0 in) equaled the 45.0-in minimum length limit, but was less than the 50.0-in minimum length limit used on Wisconsin's trophy waters, while the minimum ultimate size of male Muskellunge (34.0 in) was less than the statewide minimum length limit. Minimum reproductive sizes for both sexes were less than Wisconsin's trophy minimum length limits. Mean growth potential of female Muskellunge in northern Wisconsin appears to be sufficient for meeting trophy management objectives and angler expectations. Muskellunge in northern Wisconsin had similar growth potential to those in Ontario populations, but lower growth potential than Minnesota's populations, perhaps because of genetic and environmental differences.

Estimates of size- and sex-specific gear selectivity are important for making informed management decisions. Sex-specific selectivity curves may be needed for two-sex statistical catch-at-age models when information about sex ratios in the catch is unavailable. We used data from three tagging programs in Minnesota and Wisconsin to estimate the size- and sex-specific selectivity of angling and spearing for Walleyes Sander vitreus. We estimated capture selectivity (the relative catchability of each component of the population) and harvest selectivity (the combined effect of capture selectivity and the decision to retain or release a fish from a given component). These components are of interest because (1) the hooking mortality of released fish contributes substantially to total mortality, so that it is important to know how harvest and release vary by size; and (2) capture selectivity is likely similar across lakes, such that data from other lakes may provide information on capture selectivity for the lake of interest, while harvest selectivity is lake specific. Estimates were obtained using generalized linear models to determine the significance of the individual and interactive effects of length and sex on selectivity. Angling capture and harvest selectivity were both greater for females than males of every length. In contrast, spearing harvest selectivity was greater for males. For both sexes, harvest selectivity for angling and spearing peaked at around 400-450mm. The capture selectivity of anglers peaked at 350-375mm. The interaction between sex and size was significant for capture selectivity for angling, with the sex effect for small fish being less than that for large fish. Above 400mm, spearing selectivity did not appear to vary with length for either sex, but at lengths below that it was lower for males.Received March 20, 2013; accepted October 29, 2013

The sea lamprey, Petromyzon marinus , is a harmful invader of the Laurentian Great Lakes. The odor emitted by larval lampreys resident to streams attracts migrating adults to high quality spawning habitats. Three components of the larval pheromone have been identified and tested in laboratory settings: petromyzonol sulfate, petromyzosterol disulfate, and petromyzonamine disulfate. Here, we report the first field test of six mixtures of synthetic versions of these pheromone components, and we compare lamprey responses to these with those elicited by the complete larval odor in a natural stream. Exposure to larval odor both increased upstream movement and attracted migrants into the portion of a channel containing the odor. No tested combination of synthetic pheromone components proved similarly attractive. These findings suggest the existence of unknown additional components of the pheromone that await discovery and are likely necessary if the pheromone is to be useful in management of this pest. Further, we hypothesize that the complete pheromone mixture is necessary to attract migrants into spawning habitat at the conclusion of the migration, whereas a partial pheromone may be effective at the transition from lake to stream when natural factors both dilute and alter the ratio of components from that actually emitted by sea lamprey larvae.

The female sea lamprey (Petromyzon marinus), a devastating invasive fish of the Laurentian Great Lakes, locates potential mates by tracking a sex pheromone emitted by nesting males. We tested whether combinations of two putative components of the sex pheromone, 3-keto-petromyzonol sulfate (3kPZS) and 3-keto-allocholic acid (3kACA), were sufficiently attractive to function as a trap-bait when placed in direct competition with male odors. Ovulating females successfully located point sources of 3kPZS both in the presence and absence of a competing odor emitted by mature males placed upstream. However, 3kPZS was not able to retain females in the vicinity of a trap longer than two minutes, and retention time was reduced by 57% when competing male odors were present. 3kACA failed to elicit a response on its own and did not improve attraction to, or retention near, a source of 3kPZS. Application of an incomplete pheromone in trapping-for-control scenarios will require devices configured to minimize the effort necessary to enter a trap, features to offset the probable decrease in trap retention, and deployment into favorable habitats where competition with spawning males is minimal.