The following criteria were used for selecting lakes during the toolbox initiative in 2003, and

are again recommended for any additional lakes where new length regulations are considered

for northern pike.

A) Assessment of recruitment;

B) Assessment of growth;

C) Connectivity to other waters; and

D) Social considerations (described in muskellunge management on pages 42-45).

Selection of regulations for northern pike relies primarily on correct assessment of

recruitment (reproductive success). Because we do not have direct measures of recruitment,

the extent of recruitment must be judged by combinations of gill net catch rates, assessments

of available spawning habitat, evaluations of stocking practices, and (if available) population

density estimates. Where we have density estimates, densities of 6 fish (14 inches and larger)

or less per acre are indicative of low recruitment. Gill net catch rates associated with low

recruitment are often less than 5 fish/net. Examples of lakes with moderate recruitment had

gill net catch rates of 6-10 fish/net and high recruitment would likely be more than 10

fish/net. Evaluations of stocking and available spawning habitat will be judgments by field

staff. Low recruitment typically results in good growth rates. Average back calculated

lengths at age for low density/low recruitment populations have been at least the following:

Average length (inches)

Age Males Females

2 16.1 16.8

3 19.6 21.1

4 21.6 23.5

Growth information by sex should be provided and evaluations of regulations should include

growth data collected by sex. Providing age distribution of gill net catches may also make it

possible to calculate mortality rates for the population. Low recruitment/low density

populations typically have average lengths in gill net catches of 21 inches or greater and

good populations may be over 24 inches. Proportional stock densities (PSD = ratio of

numbers of quality size to stock size fish; see Anderson and Gutreuter 1983) of greater than

40% are also indicative of low density populations. Moderate recruitment lakes had average

lengths of 18-22 inches (usually less than 21 inches) and PSDs of 18-60% (usually less than

40%) in gill net catches.

Lake basins that are broadly connected with other basins make enforcement and evaluation

of regulations more difficult. A further consideration is that high rates of development along

a lakeshore make it difficult to communicate collectively with lakeshore owners compared to

lakes with predominantly state or federal ownership.

Evaluation periods for new regulations should be a minimum of 10 years, and preferably 15

years since individual fish can live for 14 years or more. Evaluations will consist of some

combination of spring trap netting, spring short term gill netting, and routine summer

population assessment netting every five years. Uniformly made multimesh experimental gill

nets for summer assessment netting have been used as the standard technique for monitoring

fish populations in Minnesota since 1941 (Moyle et al. 1950). Trap netting in early spring

during ice-out and spawning is an effective method for sampling large numbers of pike. Trap

nets are set along shorelines and take advantage of the tendency of pike to move into the

warmest water they can find as the ice is receding. Spring short term gill netting consists of

setting nets for 3-4 hours during the morning or mid day while water temperatures are still

changes in relative abundance and lengths of fish in the pike population. Similar long term

information does not exist for spring trapping and short term gill netting. All three methods

are useful for examining the size structure of pike populations; however, maximum length of

pike observed is usually larger from spring trap netting. Catch rates from summer assessment

netting correlate very well with population density estimates whereas spring trapping and

short term gill netting do not. Criteria for evaluating regulations consist of changes in relative

abundance (catch rates) of northern pike and other fish species, and changes in average

length and proportions of various sizes of pike (e.g. PSD). Observed changes are compared

to similar parameters in reference lakes without length regulations.

Special regulations are implemented following the process for exempt permanent rules

(Minn. Stat. Sec. 97C.005). Public input for making decisions is essential to gain

understanding and support for a successful management program. Involving the public

provides a means for incorporating the public’s values, interests, needs, and desires into

decisions that affect their lives, and encourages the public to provide meaningful input into

the decision process (IAPP 2006). It is the agency’s responsibility to provide the necessary

information so that the public can participate in a meaningful way. The following steps and

timeline describe the decision making and public input process for new special regulation

waters.

1) Area Fisheries Manager contacts stakeholders to initiate discussions and get initial

input on proposed changes. In some cases interested stakeholders initiate the request

by contacting the area fisheries office.

2) Area Fisheries Manager submits a written proposal (described in Appendix F) for

Regional and Statewide Review in January.

3) Proposals are reviewed and approved by the Division of Fish and Wildlife for broad

public input by March.

4) Notice of proposed management change published in local and statewide newspapers

between 60 and 90 days before a public meeting (during the open water angling

season). Signs posted at public accesses for a minimum of 90 days. Date(s) of public

meetings will be posted on the DNR website. Interested stakeholders should contact

the area fisheries office for information on the proposed change.

5) Notice of proposed management change published in local and statewide newspapers

within 30 and 7 days of public meeting.

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6) A public meeting is held in county where largest portion of water is located and in St.

Paul Central Office if the proposed water is 1,500 acres or larger.

7) Summary of public input and Area Managers recommendation submitted with final

proposal by October/November.

8) Section of Fisheries Management submits recommendation to Division Management

Team and Commissioners office for approval in November.

9) Decision to proceed incorporated into fisheries synopsis by December.

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