Joshua L. McCormick

Effect of Fishing Success on Angler Satisfaction on a Central Oregon Rainbow Trout Fishery: Implications for Establishing Management Objectives

AbstractUnderstanding the relationship between fish populations, fishing success, and angler satisfaction is critical for effective fisheries management. Our objectives were to quantify angler satisfaction in a fishery for Rainbow Trout Oncorhynchus mykiss in central Oregon and examine the factors influencing angler satisfaction. Multinomial logistic regression models were used to determine the effect of several variables, including fishing success, on angler satisfaction. Measures of fishing success were present in all of the top candidate models. The probability of an increase in angler satisfaction rating was positively related to mean length and number of fish caught per hour. However, younger anglers tended to have higher satisfaction ratings at lower mean length and catch rates of fish than did older anglers. These models provided information on the expected percentage of anglers that will be satisfied given the average length of fish caught and the number of fish caught per hour. These results can ...

Creel Survey Sampling Designs for Estimating Effort in Short-Duration Chinook Salmon Fisheries

Abstract Chinook Salmon Oncorhynchus tshawytscha sport fisheries in the Columbia River basin are commonly monitored using roving creel survey designs and require precise, unbiased catch estimates. The objective of this study was to examine the relative bias and precision of total catch estimates using various sampling designs to estimate angling effort under the assumption that mean catch rate was known. We obtained information on angling populations based on direct visual observations of portions of Chinook Salmon fisheries in three Idaho river systems over a 23-d period. Based on the angling population, Monte Carlo simulations were used to evaluate the properties of effort and catch estimates for each sampling design. All sampling designs evaluated were relatively unbiased. Systematic random sampling (SYS) resulted in the most precise estimates. The SYS and simple random sampling designs had mean square error (MSE) estimates that were generally half of those observed with cluster sampling designs. The S...

Sample Size Estimation for On-Site Creel Surveys

AbstractConducting sample size analysis is important to ensure that sample sizes are adequate to meet objectives for precision but not so large that valuable resources are wasted. When simple survey designs are used, sample size analysis is straightforward. However, creel surveys often follow complex designs that can make sample size estimation difficult. The objectives of this study were to provide sample size estimators for commonly used creel survey designs and investigate sample size requirements to achieve varying levels of precision. For estimates of angling effort, the average sample size among fisheries required to achieve relative 95% confidence intervals of 40% (i.e., coefficient of variation of approximately 0.2) was 16 d (range = 7–40 d). To estimate mean catch rate with the same level of precision, 43 survey days (range = 8–95 d) were required when the daily catch rate estimator was used, and 11 d (range = 3–30 d) were required when the multi-day estimator was used. Fifty-five days (range = 1...

Evaluation of Methods to Estimate Salmon Harvest Using Angler Harvest Permits Available on a Smartphone Application

AbstractChinook Salmon Oncorhynchus tshawytscha harvest in Oregon is currently estimated using voluntary returns of angler harvest permits. However, estimates are potentially biased due to nonresponse. The objective of this study was to evaluate the utility of a new method for estimating harvest in which anglers were given the option to record harvest on a smartphone application in addition to traditional paper harvest permits. Estimates were evaluated via simulation using eight basins along the mid- and north coast of Oregon as a theoretical case study. Simulated harvest was estimated using data from supplemental on-site surveys in conjunction with hypothetical harvest data recorded on smartphones. Confidence intervals varied from 1.2% to 24.7% of actual harvest at the aggregate scale and from 2.6% to 104.1% at the individual-fishery scale when smartphone recording rates were consistent among fisheries. Precision increased as the percentage of anglers recording harvest on a smartphone increased. Based on...

Using Tag-Return Models to Estimate the Number of Times Fish Are Captured in Fisheries with High Catch-and-Release Rates

AbstractExploitation rates are often estimated using tag-return studies. However, in fisheries with a catch-and-release component, exploitation rate or fishing mortality may not be the most important metric of interest. Instead, angler catch rates (e.g., fish caught per hour), total catch (including fish that are harvested or released), or the average number of times an individual fish is caught may be a better measure of fishery performance. However, if anglers remove tags from fish before release, then catch estimates will be negatively biased because tag removal will not be accounted for. In this study, maximum likelihood estimation methods were used to estimate catch in fisheries with high rates of catch and release. Right-censored models were used to accommodate tags that may or may not be removed by anglers. Model-derived maximum likelihood estimates of mean catch were relatively unbiased under two simulated fishery scenarios. There was a nonlinear, positive relationship between the percentage of ta...

Feasibility and Evaluation of Probabilistic On-site Surveys for Estimating Angler Use and Catch in High Mountain Lakes

AbstractEstimating angling effort and catch at high mountain lakes can be difficult due the abundance, remoteness, and diffuse nature of angling effort that typify high mountain lake fisheries. In this study, a simulation was used to evaluate the accuracy of catch and effort estimates derived using on-site access–access and roving–access creel surveys at a complex of 35 high mountain lakes. Five levels of angling effort and catch at the 35 lakes were simulated, and effort varied from 3,278 to 68,741 h and catch varied from 1,737 to 50,525 fish over the duration of the season. Access–access creel surveys had an average of 32% relative error and roving–access surveys had an average of 17% relative error in estimates of aggregate (i.e., at all 35 lakes) angling effort and catch when one creel surveyor was used. Estimates were relatively robust to temporal and spatial changes in patterns of effort and catch rate over the duration of the season. Relative error was inversely related to the amount of angling eff...

A Simulation Assessment of Model-Assisted Estimation of Steelhead Redd Abundance

AbstractRedd abundance for steelhead Oncorhynchus mykiss is frequently estimated using design-based redd surveys. Redd abundance estimates may be biased low because redds may not be distinguishable prior to or in between sampling events (i.e., removal bias). Removal bias is typically mitigated by increasing temporal sampling intensity, thereby potentially reducing the level of spatial replication. In this study a model-assisted estimation technique to correct for removal bias was described and evaluated. Parametric survival time models were fit to redd data to estimate redd longevity and parameterize a simulation to evaluate the model-assisted estimation approach. The simulation showed increasing negative bias in redd counts not adjusted for removal bias as redd longevity decreased and as sampling intervals increased. Average bias among simulated datasets was as high as 43% using raw counts when redd longevity was relatively short at a 25-d sampling interval. Average bias was reduced to as low 1.3% using ...