Surface temperature and precipitation variations in the western U.S. and their relation to large scale circulation indices [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): An analysis of the principal components of surface temperature and precipitation in the western U.S. is presented. Data consist of monthly mean temperature and total precipitation for 66 climate divisions west of the Continental Divide, for the years 1931-1984. The analysis is repeated for three separate combinations of months - the water year (Oct - Sept), the cool season (Oct - Mar) and the warm season (Apr - Sept). Inspection of monthly precipitation climatology indicates that selection of these combinations of months results in very few awkward splittings of the natural precipitation seasons found in the West.

Abundance of cetatceans in the southern U.S. North Atlantic Ocean during summer 1998

The U.S. Marine Mammal Protection Act requires that the abundance of marine mammals in U.S. waters be assessed. Because this requirement had not been met for a large portion of the North Atlantic Ocean (U.S. waters south of Maryland), a ship-based, line-transect survey was conducted with a 68 m research ship between Maryland (38.00°N) and central Florida (28.00°N) from the 10-m isobath to the boundary of the U.S. Exclusive Economic Zone. The study area (573,000 km2) was surveyed between 8 July and 17 August 1998. Minimum abundance estimates were based on 4163 km of effort and 217 sightings of at least 13 cetacean species and other taxonomic categories. The most commonly sighted species (number of groups) were bottlenose dolphins, Tursiops truncatus (38); sperm whales, Physeter macrocephalus (29); Atlantic spotted dolphins, Stenella frontalis (28); and Risso’s dolphins, Grampus griseus (22). The most abundant species (abundance; coeffi cient of variation) were Atlantic spotted dolphins (14,438; 0.63); bottlenose dolphins (13,085; 0.40); pantropical spotted dolphins, S. attenuate (12,747; 0.56); striped dolphins, S. coeruleoalba (10,225; 0.91); and Risso’s dolphins (9533; 0.50). The abundance estimate for the Clymene dolphin, S. clymene (6086; 0.93), is the first for the U.S. Atlantic Ocean. Sperm whales were the most abundant large whale (1181; 0.51). Abundances for other species or taxonomic categories ranged from 20 to 5109. There were an estimated 77,139 (0.23) cetaceans in the study area. Bottlenose dolphins and Atlantic spotted dolphins were encountered primarily in continental shelf (<200 m) and continental slope waters (200−2000 m). All other species were generally sighted in oceanic waters (>200 m). The distribution of some species varied north to south. Striped dolphins, Clymene dolphins, and sperm whales were sighted primarily in the northern part of the study area; whereas pantropical spotted dolphins were sighted primarily in the southern portion.

The statistical properties of recreational catch rate data for some fish stocks off the northeast U.S. coast

Recreational fisheries in the waters off the northeast U.S. target a variety of pelagic and demersal fish species, and catch and effort data sampled from recreational fisheries are a critical component of the information used in resource evaluation and management. Standardized indices of stock abundance developed from recreational fishery catch rates are routinely used in stock assessments. The statistical properties of both simulated and empirical recreational fishery catch-rate data such as those collected by the National Marine Fisheries Service (NMFS) Marine Recreational Fishery Statistics Survey (MRFSS) are examined, and the potential effects of different assumptions about the error structure of the catch-rate frequency distributions in computing indices of stock abundance are evaluated. Recreational fishery catch distributions sampled by the MRFSS are highly contagious and overdispersed in relation to the normal distribution and are generally best characterized by the Poisson or negative binomial distributions. The modeling of both the simulated and empirical MRFSS catch rates indicates that one may draw erroneous conclusions about stock trends by assuming the wrong error distribution in procedures used to developed standardized indices of stock abundance. The results demonstrate the importance of considering not only the overall model fit and significance of classification effects, but also the possible effects of model misspecification, when determining the most appropriate model construction.