Operational Plan for the Restoration of Diadromous Fishes to the ...

Appendix H - Developing a Sampling Plan for the Penobscot Basin
Author: Greg Mackey
Introduction
The Penobscot Basin is the largest river system in Maine and is managed for
Atlantic salmon and other diadromous fishes in the context of a state-wide setting.
Sampling natural systems for management requires unbiased and spatially
distributed sampling, with samples spaced relatively evenly in space. Sampling
must balance trend and status data collection goals. In addition, sampling should
allow for greater emphasis (sampling) effort within certain areas depending on needs
of biologists and managers. Finally, sampling must be flexible to allow un-sampled
sites to be accounted for, and to add sites as needed. This requires a probability
sampling approach. Without probability sampling we cannot understand how
samples represent the “real world’ and are likely to collect biased data that may
result in incorrect conclusions and inform poor management decisions. Clearly, this
is vital for effective adaptive management. Furthermore, collecting data under a
unified probability sampling plan with standardized protocols will greatly increase
statistical power for the same level of sampling effort, allowing biologists to more
powerfully analyze large spatial and temporal trends and status. Finally, the
sampling plan for the Penobscot should be integrated with a larger state-wide
sampling plan to increase statistical power and optimize the value of limited
sampling capacity.
Such surveys are constructed using several components: The Master Sample
concept is used to unify sampling that is performed by many different entities, such
as state-wide sampling. It requires 1) sampling from the same frame, and 2) using
standardized sampling methods. Sampling Frame defines the domain from which
samples are drawn (e.g. the river network or collection of all river networks in the
state). Multi-density categories are attributes of the frame that allow the sampling
design to specify sampling effort based on the attribute (such as stream order).
Stratification allows the frame to be divided into units of interest for sampling, and
strata may have differing sampling designs based on needs. Panels allow the
sampling design to incorporate multi-year designs so rotating samples may be used.
Oversample allows the sampling design to specify “extra” samples that can be used
if needed. These samples are consistent with the sampling design.
Sampling activities in the Penobscot that require a probability sample include
juvenile salmon surveys (electrofishing or snorkeling), and redd surveys. In addition,
surveys of habitat characteristics such as water temperature, water quality, or
habitat features such as large woody debris or stream canopy cover may benefit
from using probability sampling.
We used the spsurvey package for R, developed by the US Environmental
Protection Agency Environmental Monitoring and Assessment Program. This
package allows the creation of generalized random-tessellation stratified sampling
PRFP Page 190