Part I – Stocking Trout…It’s All in the Numbers
By Pat Hamilton, Principal Fisheries Biologist
Part I – Stocking Trout…It’s All in the Numbers
By Pat Hamilton, Principal Fisheries Biologist
The popularity and success of this program is due in large part to Fish & Wildlife’s trout stocking program. Over the last century, millions of trout raised in our state-run hatcheries have provided outdoor recreational fun for countless children and adults. Yet most anglers are not familiar with the inner workings of this program. This article, Part I of a multi-part series, offers a behind-the-scene glimpse of the methodology used to allocate our hatchery-reared trout.
Prior to 1990, the statewide trout allocation was based on a tradition that heavily relied upon political boundaries. Back then, each of the 21 counties had their “trout quota” and the Fish and Game Council would determine the number of trout stocked in each waterbody. When a waterbody was dropped from the stocking program, it was common practice to redistribute those trout to other trout-stocked waters within that county. Council members, when besieged with requests from anglers, would also vie for more trout for their county of interest. The unpredictability in the number of trout produced—at that time from the Hackettstown Hatchery—compounded this allocation dilemma. Thus, over time there developed some glaring inequities in the number of trout allocated to individual waters.
When the state of the art Pequest Trout Hatchery was constructed in the early-1980s, its cold and dependable well water enabled us to consistently rear a predictable number of trout annually. With a stable supply of cultured trout assured, efforts then turned to the development of a more equitable method to allocate trout statewide. After much trial and error, which included a 1989 public forum to solicit input from anglers, the “Trout Stocking Improvement Plan” was implemented the following year. At the heart of this plan, and still in use today (with a few “tweaks” over the years), is a trout allocation methodology that uses a database and formulas to derive the weekly spring trout allocations for nearly 200 ponds, lakes and streams statewide. The underlying principle of this methodology is that trout-stocked waters with similar characteristics are stocked with a similar number of trout.
How are the spring trout allocations determined?
Each pond, lake and stream (or stream segment) is listed in our computer database and characterized using a suite of physical, biological and social attributes. The physical size of a waterbody plays the largest role in determining the individual trout allocations. Streams are separated into five categories based upon their size (flow) and each size category is assigned a stocking rate. Large streams like the lower Musconetcong River have the highest rate (485 trout per mile, pre-season); our smallest streams have the lowest rate (135 trout per mile, pre-season).
Lakes and ponds are divided into three size categories based on surface area; a sliding-scale stocking rate is used. For the pre-season period, this rate is 75 trout per acre for the first 5 acres, five trout per acre for the next 6–30 acres and one trout per acre for each additional acre over 30 acres. The sliding scale is necessary because if large lakes were stocked at the same rate as small ponds, the supply of trout would quickly be exhausted by just a few large lakes.
For each stream, the appropriate stocking rate is multiplied by the stream mileage. This mileage is determined by assigning 1⁄2 mile to each stocking point (1⁄4 mile above and below each point, discounting overlap and dams that prevent upstream fish movement). For lakes and ponds the appropriate stocking rate(s) is applied using their surface acreages.
Next, these initial allocations are adjusted using biological and social attributes. The biological attributes characterize the trout fishery in each water as either seasonal (trout survival in the summer is minimal to absent) or year round (trout thrive throughout the year). Those waters able to support trout year round have their allocation increased by 10 percent.
Adjustments are also made using social attributes, which describe conditions that enhance or limit fishing. The social attributes for streams are land ownership (percent publicly owned), availability of parking and angler interest. These factors affect the anglers’ ability to fish the stream and describe the intensity of usage. For example, an allocation is increased by 10 or 20 percent if the stream has good parking, flows through public land, and is very popular. However, if conditions are less than ideal, then a stream’s allocation might remain unchanged or be reduced by 10 or 20 percent, depending on the extent of its social limitation.
On lakes and ponds, the human population density, number of nearby trout fishing opportunities and shoreline/boating access is considered. Those near high population areas receive 10 or 30 percent more trout, because they serve a large number of anglers. If other trout fishing opportunities (within a 10-mile radius) are limited, then the allocation would increase 30 percent (no opportunities) or 10 percent (1–5 opportunities).
Once the allocations are adjusted by biological and social factors, the result is the number of trout the waterbody receives prior to opening day, referred to as the pre-season allocation. Typically, most waterbodies receive the greatest number of trout pre-season, and lesser quantities of trout each time they are stocked in season (after opening day). Each in-season allocation is a strict percentage of the pre-season allocation.
Larger streams are stocked more often than smaller streams because they are more heavily fished and have more water. The first in-season stocking on streams is usually 40 or 45 percent that of the pre-season allocation and this percentage dwindles to 25 percent by the end of the season (when water temperatures rise and flow subsides). The only exception is for small streams, which receive so few trout to begin with that the pre- and in-season allocations are identical. Lakes and ponds are typically stocked three times after opening day, with 75 percent of the pre-season allocation each time. A fourth stocking is added if the waterbody is near a populated area.
The last step in the trout allocation methodology involves one final set of adjustments. When the individual allocations are totaled statewide, the sum must equal the number of trout available for spring stocking—570,000 trout—Pequest hatchery’s annual spring baseline. All the allocations are proportionally adjusted to achieve this baseline figure. Finally, all allocations are rounded to the nearest multiple of ten. With this last adjustment the grand total is very close (but seldom exactly equal) to 570,000 trout.
Though this trout allocation methodology may seem complicated, it provides us with the means to allocate trout equitably. Larger waters receive more trout than smaller waters. Good trout streams and lakes in north Jersey having year round fisheries are rewarded with more fish, but so too are the far-flung lakes and ponds in central and south Jersey that don’t support trout year round. A more detailed explanation of the allocation methodology can be found in Fish and Wildlife’s Coldwater Fisheries Management Plan, available at NJFishandWildlife.com.
How often are changes made to the database and formulas?
The database is reviewed and updated annually. Therefore, the allocations for an individual waterbody may change from year to year as a result of program and database changes.
Where can I find the allocation numbers?
The spring allocations are announced at the public meeting held each February at the Pequest Trout Hatchery and then posted, along with the in-season stocking schedule, on Fish and Wildlife’s Web site.
How can I get more trout stocked in my favorite lake or stream?
The trout allocation for a waterbody stays about the same from year to year unless circumstances there have changed. Circumstances seldom change at ponds and lakes. Their physical size doesn’t change, and the other biological and social factors previously described remain fairly constant. On the other hand, the allocations for streams can fluctuate from year to year. When stocking points on a stream are added or dropped, the stream mileage figure must be adjusted, in turn affecting the allocation. Also, when land ownership along a trout-stocked stream section changes from private to public, increasing public access, a stream’s allocation may increase accordingly.
Are the fall and winter trout allocations calculated the same way as the spring allocations?
The fall baseline for streams is 16,700 trout and each fall-stocked stream is proportionally allocated based upon their pre-season allocation. The baseline for lakes and ponds in the fall (3,300 trout) and winter (5,000) and their individual allocations were set when these stocking programs were established; the individual allocations have changed very little over the years.
I know a waterbody that would be great for trout fishing. Can Fish and Wildlife stock it with trout?
While it would be great to expand the trout stocking program and add new waters to the list, it is important to understand there is a finite number of trout available for stocking. If more waters are stocked, existing stocked waters will receive fewer fish and trout fishing in those waters could suffer.
Additionally, in order for a waterbody to be stocked with trout, it must be formally incorporated into the listing of trout stocked waters in the New Jersey Fish Code. Every two years the Fish and Game Council reviews requests from the public for stocking changes plus recommendations from agency biologists, and then decides which waterbodies to include in a formal proposal. Following a public hearing, the proposal is adopted with or without changes. Requests for changes to the Fish Code for the 2014–2015 fishing season should be submitted to the Council by September, 2012.
What else does Fish and Wildlife do under its trout program, besides stock trout?
A less visible, but equally important component of our trout program is the research and management activities. These range from surveys in lakes and streams to assess their trout fisheries, to the development of trout fishing regulations, to protection of water quality and habitat. In the 2012 freshwater edition of this Digest, Part II of this series will explore interesting aspects of Fish and Wildlife’s trout research and management programs. Don’t miss it!