Analysis using optimal stratification with latitude and longitude as covariates and combining strata 7 and 8.

Figure 1 Map of strata from the optimal stratification and allocation proceedure using latitude and longitude as covariates. Latitude and longitude boundaries and individual sampling sites are color coded by strata. Stratum 1 (Blue) is the most southerly and they proceed in order in a northerly direction to Stratum 7 (Maroon).
Figure 1 Map of strata from the optimal stratification and allocation proceedure using latitude and longitude as covariates. Latitude and longitude boundaries and individual sampling sites are color coded by strata. Stratum 1 (Blue) is the most southerly and they proceed in order in a northerly direction to Stratum 7 (Maroon).


Figure 2. Chevron trap abundance index mean annual coefficient of variation (CV) by species, sample size, reduction magnitude, and sampling scheme (Simple Random Sample=no stratification, multiple regression tree (MRT) Stratified with Equal Allocation=multiple regression tree (MRT) stratification with equal sample allocation among strata, MRT Stratified with Bethel Allocation= MRT stratification with sample allocation among strata computed with the Bethel Algorithm, and Optimal Stratification and Allocation=optimal stratification and allocation with latitude and longitude covariates).
Figure 2. Chevron trap abundance index mean annual coefficient of variation (CV) by species, sample size, reduction magnitude, and sampling scheme (Simple Random Sample=no stratification, multiple regression tree (MRT) Stratified with Equal Allocation=multiple regression tree (MRT) stratification with equal sample allocation among strata, MRT Stratified with Bethel Allocation= MRT stratification with sample allocation among strata computed with the Bethel Algorithm, and Optimal Stratification and Allocation=optimal stratification and allocation with latitude and longitude covariates).


Figure 3. Video abundance index mean annual coefficient of variation (CV) by species, sample size, reduction magnitude, and sampling scheme (Simple Random Sample=no stratification, multiple regression tree (MRT) Stratified with Equal Allocation=multiple regression tree (MRT) stratification with equal sample allocation among strata, MRT Stratified with Bethel Allocation= MRT stratification with sample allocation among strata computed with the Bethel Algorithm, and Optimal Stratification and Allocation=optimal stratification and allocation with latitude and longitude covariates).
Figure 3. Video abundance index mean annual coefficient of variation (CV) by species, sample size, reduction magnitude, and sampling scheme (Simple Random Sample=no stratification, multiple regression tree (MRT) Stratified with Equal Allocation=multiple regression tree (MRT) stratification with equal sample allocation among strata, MRT Stratified with Bethel Allocation= MRT stratification with sample allocation among strata computed with the Bethel Algorithm, and Optimal Stratification and Allocation=optimal stratification and allocation with latitude and longitude covariates).


Figure 4. Chevron trap abundance index mean annual coefficient of variation (CV) by species and sample size for simple random sampling and optimal stratification and allocation.
Figure 4. Chevron trap abundance index mean annual coefficient of variation (CV) by species and sample size for simple random sampling and optimal stratification and allocation.


Figure 5. Video abundance index mean annual coefficient of variation (CV) by species and sample size for simple random sampling and optimal stratification and allocation.
Figure 5. Video abundance index mean annual coefficient of variation (CV) by species and sample size for simple random sampling and optimal stratification and allocation.


Figure 5. True proportion of SERFS samples during last five years of sampling (2017-2019, 2021-2022) allocated to strata defined by the optimal stratification and sample allocation procedure. Optimal sample allocation proportions to each stratum (Optimal) are shown for comparison.
Figure 5. True proportion of SERFS samples during last five years of sampling (2017-2019, 2021-2022) allocated to strata defined by the optimal stratification and sample allocation procedure. Optimal sample allocation proportions to each stratum (Optimal) are shown for comparison.