Gaylord R. Alexander

Sand Bed Load in a Brook Trout Stream

Abstract An experimental introduction of sand sediment into Hunt Creek in the northern Lower Peninsula of Michigan that increased the bed load 4-5 times resulted in a significant reduction of brook trout (Salvelinus fontinalis) numbers and habitat. The brook trout population declined to less than half its normal abundance. The growth rate of individual fish was not affected. Population adjustment to the poorer habitat was via a decrease in brook trout survival rates, particularly in the egg to fry and/or the fry to fall fingerling stages of their life cycle. Habitat for brook trout and their food organisms became much poorer, as judged by the drastic reductions of both. Stream morphometry changed considerably, the channel becoming wider and shallower. Furthermore, sand deposition aggraded the streambed and eliminated most pools. The channel became a continuous run rather than a series of pools and riffles. Water velocities increased, as did summer water temperatures. Relatively small sand bed-load concent...

Hooking Mortality of Trophy-Sized Wild Brook Trout Caught on Artificial Lures

Abstract The average hooking mortality per capture event for 630 trophy-sized wild brook trout Salvelinus fontinalis (mean total length, 33.9 cm) caught on five hardware lures was 4.3% during the first 48 h after capture, Mortality was 8.3% for brook trout caught on Mepps spinners and Cleo spoons equipped with a treble-pointed hook, whereas mortality was significantly lower (2.4% per hooking event; P < 0.05) for fish caught on the same lures with a single-pointed hook. The 10.9% mortality caused by treble-hook Mepps spinners was significantly higher than mortality caused by single-hook Cleo spoons (1.6%). Mortality for brook trout caught on single-hook Cleo spoons and single-hook Mepps spinners combined (2.4%) was also significantly lower (P < 0.05) than mortality offish caught on Mepps spinners with treble hooks. There was no mortality among 126 brook trout caught with Rapala lures rigged with two treble hooks. We believe that the differences in mortality of brook trout caught with different lures are pr...

Mathematical Description of Trout-Stream Fisheries

Abstract A mathematical model of trout-stream fisheries was developed that can be used to evaluate a variety of fishing regulations. Density-dependent mortality was found in the first 2 years of life for each of the two brook trout (Salvelinus fontinalis) and three brown trout (Salmo trutta) populations studied in Michigan. Regression equations were used to describe the density-dependent relationships for modeling purposes. Equations were developed that used mortality, growth, and length-frequency information to calculate the number of fish in a population, number caught and harvested, number caught and released, number of deaths due to hooking mortality, number of natural deaths, and number recruited for any time period and age-group. Also, addition of a length-weight regression allowed equations to be developed for calculating yield in weight harvested, yield in weight caught and released, and gross biomass production for any time period and age-group. Effects of imposing different types of length limit...

Sand Sediment in a Michigan Trout Stream Part II. Effects of Reducing Sand Bedload on a Trout Population

Abstract This is the second of a two-part sedimentation study. A sediment basin excavated in a Michigan trout stream reduced the sandy bedload sediment by 86% (from 56 ppm down to 8 ppm). Following the reduction in bedload, trout numbers increased significantly during the next 6 years. Small or young trout increased about 40% throughout the treated area. Larger and older trout increased in that part of the treated area that had an erodible sand bed. Although trout production increased 28%, growth rate of the trout changed but little. Both brown trout (Salmo trutta) and rainbow trout (Salmo gairdneri) populations responded similarly to the bedload reduction. However, statistical tests were more conclusive for brown trout than for rainbow trout because of the lower year-to-year variation of the brown trout population. The results suggested that in-stream sediment basins are an effective means for removing sand bedload and that even small amounts of moving-sand bedload sediments can have a major impact on a ...

Growth, Survival, and Vulnerability to Angling of Three Wild Brook Trout Strains Exposed to Different Levels of Angler Exploitation

Abstract It has been suggested that the genetic growth potential of trout may be degraded over time by differential angler harvest of the faster-growing fish of each cohort. To test this hypothesis, young-of-the-year wild brook trout Salvelinus fontinalis from two branches of the Au Sable River and from the East Branch of the Fox River were stocked in three experimental Michigan lakes to determine their relative 2-year growth and survival. Brook trout populations from the Au Sable River are believed to have been exploited more intensively than the population from the East Branch of the Fox River. We found that brook trout from the East Branch Fox River grew significantly faster than fish from either the North Branch or the mainstream Au Sable River. The superior growth of East Branch Fox River brook trout was most evident in Hemlock Lake, where all strains grew best. Mature males were significantly longer and heavier than mature females when data were pooled across strains for each lake, East Branch Fox R...

A History and Evaluation of Regulations for Brook Trout and Brown Trout in Michigan Streams

Abstract Since establishment of the Board of Fish Commissioners in 1873, the trend in Michigan trout fishing regulations has been toward more restrictive and complex laws. Major scientific investigations concerning the effectiveness of various types of regulations began in 1945. Those studies indicated that a minimum size limit was the most effective regulation for controlling exploitation of trout. In this study, minimum size limits for brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) in Michigan streams were evaluated through mathematical modeling. Minimum size limits ranging from 152 to 229 mm were tested for brook trout and from 152 to 305 mm for brown trout. Catch-and-release (no-kill) regulations were also simulated for both species. Maximum yield in numbers and weight of trout harvested (legal-size fish killed) was obtained at a 152-mm minimum limit for both species. Yield in numbers and weight of trout caught and released (sublegal fish returned to water alive) increased as size ...

Results of Predator Reduction on Brook Trout and Brown Trout in 4.2 Miles (6.76 km) of the North Branch of the Au Sable River

Abstract During the autumns of 1964, 1965 and 1966, brown trout 12.0–25.1 inches (305–638 mm) in length were removed from 4.2 miles (6.76 km) of the North Branch of the Au Sable River (Dam 2-County Line), and American mergansers were harassed in the same area each winter as time permitted. The objective was to decrease losses among the smaller salmonids which would otherwise be eaten by the large trout and mergansers. Effects of control efforts were assayed by comparison of 1965–1967 angling results and population estimates with similar data accumulated on the test section and two other stream sections of the North Branch during 1961–1964 when predator manipulation was not carried on. In 1964, 561 large brown throut (66% of the estimated population) were removed. In 1965 and 1966, the actual removals were 346 and 104, or 63 and 40% of the population, respectively. The only major change noted was an increase during 1965, 1966 and 1967 in numbers of brook trout larger than 9 inches (229 ram) in the populati...

A Modified Inclined-Screen Trap for Catching Salmonid Smolts in Large Rivers

Abstract A modification of the inclined-screen trap was constructed to capture and facilitate processing of runs of salmonid smolts in large rivers. Modifications included a hanging inclined screen, a floating catch barge, and a fish sorter. Two such traps operated in the Little Manistee River in northwestern Michigan caught and held up to 2,500 steelhead (Salmo gairdneri) smolts per night. By sampling only a portion of the total river flow and using pipe weirs to guide smolts toward the two traps, we successfully sampled the smolt migration during periods of fluctaating water levels and debris content. It was estimated that our trapping scheme caught 42% of the steelhead smolts, 31% of the chinook salmon (Oncorhynchus tshawytscha) smolts, and 22% of the coho salmon (Oncorhynchus kisutch) smolts migrating downstream.

Sand Sediment in a Michigan Trout Stream Part I. A Technique for Removing Sand Bedload from Streams

Abstract Techniques for erosion control such as stream-bank stabilization and revegetation of eroding upland areas reduce only part of a streams sediment load. This study on Poplar Creek in Michigan (one of two papers) demonstrated that an in-stream sediment basin can trap and remove almost all sand bedload sediments. Other advantages of sediment basins are that they can (1) produce downcutting to create deeper pools and improve streambed composition, and {2) keep critical fisheries spawning areas relatively free of sediment. Sediment basins should be used with caution in streams with erodible beds that have no areas of erosion-resistant streambed to prevent possible excessive downcutting. Sediment basins can be used with other techniques to improve fish habitat, or they can be used alone to renovate sand-choked streams not amenable to the usual erosion-control treatments.

Effects of a Flies-Only Restriction on Angling and on Fall Trout Populations in Hunt Creek, Montmorency County, Michigan

Abstract Effects of a flies-only regulation on angling and on fall populations of wild brook trout were tested on 5,000 feet of Hunt Creek, Montmorency County, Michigan. Complete angling records and population estimates for the period 1949-54, when all sections were fished under normal state regulations, were compared with records for the period 1955-59, when sections Z and A were fished under a flies-only regulation, and B and C continued under normal rules. Yearly totals for angling load, catch, angling quality, pounds of trout creeled, small trout released, and postseason (fall) population estimates were compared. Averages for the 5 years after the lure regulation was changed were compared with averages for the years before the change for both Z and A and the B and C controls. Also, annual totals for Z and A were related to corresponding annual totals for B and C to provide ZA/BC ratios for before-and-after comparisons. While flies only were used on Z and A (1955-59), angling pressure decreased, catch ...