Tactics of Pacific Northwest albacore fishermen - 1968, 1969, 1970

This study examines the relationship between fishing activities of Pacific Northwest albacore fishermen and the availability of albacore. Tactical responses of troll-boat fishermen were compared to changes in daily apparent albacore abundance. Tactical responses included boat aggregation and total applied effort (number of boats) within a particular area, and net daily distances traveled by individual boats and the medial center of the fleet. Apparent abundance estimates were derived from logbook catch records collected during the 1968, 1969 and 1970 seasons. Fishing power estimates of individual vessels allowed comparisons to be made of the most successful and least successful boats. In general, the most successful boats were larger, fished nearer the fleet center, traveled less net distance each day and caught more but smaller fish than the less successful boats. The magnitude of the differences between the most successful and least successful boats decreased progressively from 1968 to 1970. Apparent abundance fluctuations were synchronous in separate areas of the 1968 fishery but not in the 1969 and 1970 fisheries. Fluctuations tended to be periodic in 1969 and 1970 but not in 1968. No generalizations as to apparent abundance (patchiness, size of albacore concentrations) could be determined among years. Fishermen responded quickly to changes in apparent abundance during 1968. Boats were highly aggregated on days of high catches, and dispersed on days of low catches. Fishermen responses during 1969 were one day out of phase with catches. Boats aggregated one day after days of high catches, indicating that fishermen experienced difficulty in staying on concentrations of fish. In 1970 fishermen experienced no difficulty in staying on fish concentrations as record daily catches were reported. According to interviews and questionnaires, albacore fishermen rely heavily on inter-boat communications for planning their daily fishing tactics. A consequence of this reliance on radio communication appears to be a greater degree of boat aggregation and less willingness to scout in areas away from the central fleet area. Areas to the north and south of the central fleet were shown to have high estimates of albacore abundance but were exploited by very few boats. Greater dispersal of the fleet and use of several survey boats are suggested as a means of increasing the total fishing catch

A physical oceanographic study of the nearshore zone at Newport, Oregon

The nearshore zone at Newport, Oregon was studied during the period September, 1968 to August, 1969. Particular emphasis was placed on those physical factors affecting the distribution of pulp mill wastes discharged within the study area (referred to as Yaquina Bight in this thesis). Temperatures and seawater samples were obtained from a small boat. Nearshore and longshore currents were measured from a light aircraft using dye markers and drift bottles, respectively. Winds, waves and tides were measured from shore stations. This thesis describes the waters of the bight throughout the year and how they are affected by the effluent of the pulp mill and by seasonal oceanic and local conditions. The waters within Yaquina bight reflect the large scale seasonal oceanic conditions which occur off the Oregon coast, i.e., the summer upwelling season and the winter Davidson current season. On a smaller scale the waters of the bight are influenced by the pulp mill effluent. The effluent mixes rapidly with seawater and the mixture is generally colder, Less saline and less dense than the surrounding surface waters. The dissolved oxygen content of the mixture is also lower than the surrounding seawater. The analyses of different effluent-seawater dilutions indicated that the low oxygen content is not caused by chemical reactions of the effluent. Measurements of current velocity at a depth of two meters were regressed on concurrent measurements of the prevailing wind, waves and tide. The local wind of the hour previous to the time of observation accounted for 56.9% of the variance of the currents flowing in the north-south direction at the outfall station. The wind also accounted for 26.6% of the variance of the east-west flowing currents at the outfall station. Currents at other stations within the bight were also analyzed. The unexplained variance of the currents at the other stations was higher than those at the outfall station. Deviations between the surface current direction and the current direction at two meters ware apparently related to the season and to the wind speed. At wind speeds greater than seven meters per second the angle between the two current directions approached zero. The data did not indicate that the deeper current flowed to the left or the right of the surface current as a function of wind speed. However, during the upwelling season the current at two meters was observed to flow consistently to the left of the surface current

Comparison of the most successful and least successful west coast albacore troll fishermen

Catch data for albacore troll boats were collected from fishermen's logbooks and from dockside interviews during the 1968, 1969, and 1970 seasons. Fishing powers of these boats were calculated and used to determine the 10 most successful and 10 least successful fishermen (highliners and lowliners, respectively) who fished off Oregon and Washington. Characteristics of these two groups of fishermen were then compared. In general, highliners had longer boats and fished nearer the fleet center and along the offshore margin of the fleet. Lowliners tended to have smaller boats and fished along the trailing (south) inshore margin of the fleet. Both groups responded to changes in apparent albacore abundance by aggregating on days of high apparent abundance, although this response was less pronounced in 1969 and 1970. Highliners caught significantly smaller (but more) fish than the lowliners

Catches of albacore at different times of the day

The purpose of this study is to examine the hypothesis that diel variations occur in the catches of albacore by boats trolling surface jigs off Oregon. Although albacore fishermen talk of "morning bites" and "evening bites," no published data exist, to our knowledge, confirming these trends. Studies on the feeding habits of tunas, however, provide evidence for intense feeding activity during certain periods of the day. Based on the quantity of food in stomachs, Iverson (1962) concluded that major feeding periods of albacore occurred in early morning and late afternoon-evening. Similarly, Nakamura (1965) and Dragovich (1970) found evidence for morning and late afternoon peaks in the stomach fullness of skipjack and yellowfin tunas. Food consumption of captive skipjack was greatest between 0630 and 0830 h, and skipjack tuna in only one of three tanks fed intensively in late afternoon (Magnuson 1969). This was in agreement with Uda (1940) who reported that catches of skipjack tuna with pole and live bait peaked in early morning hours and were usually followed by successively lower peaks later in the day

Smaller Regional Brain Volumes Predict Posttraumatic Stress Disorder at 3 Months After Mild Traumatic Brain Injury

BackgroundBrain volumes in regions such as the hippocampus and amygdala have been associated with risk for the development of posttraumatic stress disorder (PTSD). The objective of this study was to determine whether a set of regional brain volumes, measured by magnetic resonance imaging at 2 weeks following mild traumatic brain injury, were predictive of PTSD at 3 and 6 months after injury.MethodsUsing data from TRACK-TBI (Transforming Research and Clinical Knowledge in TBI), we included patients (N = 421) with Glasgow Coma Scale scores 13-15 assessed after evaluation in the emergency department and at 2 weeks, 3 months, and 6 months after injury. Probable PTSD diagnosis (PTSD Checklist for DSM-5 score, ≥33) was the outcome. FreeSurfer 6.0 was used to perform volumetric analysis of three-dimensional T1-weighted magnetic resonance images at 3T obtained 2 weeks post injury. Brain regions selected a priori for volumetric analyses were insula, hippocampus, amygdala, superior frontal cortex, rostral and caudal anterior cingulate, and lateral and medial orbitofrontal cortices.ResultsOverall, 77 (18.3%) and 70 (16.6%) patients had probable PTSD at 3 and 6 months. A composite volume derived as the first principal component incorporating 73.8% of the variance in insula, superior frontal cortex, and rostral and caudal cingulate contributed to the prediction of 3-month (but not 6-month) PTSD in multivariable models incorporating other established risk factors.ConclusionsResults, while needing replication, provide support for a brain reserve hypothesis of PTSD and proof of principle for how prediction of at-risk individuals might be accomplished to enhance prognostic accuracy and enrich clinical prevention trials for individuals at the highest risk of PTSD following mild traumatic brain injury

Tractography-Pathology Correlations in Traumatic Brain Injury: A TRACK-TBI Study

Diffusion tractography magnetic resonance imaging (MRI) can infer changes in network connectivity in patients with traumatic brain injury (TBI), but the pathological substrates of disconnected tracts have not been well defined because of a lack of high-resolution imaging with histopathological validation. We developed an ex vivo MRI protocol to analyze tract terminations at 750-μm isotropic resolution, followed by histopathological evaluation of white matter pathology, and applied these methods to a 60-year-old man who died 26 days after TBI. Analysis of 74 cerebral hemispheric white matter regions revealed a heterogeneous distribution of tract disruptions. Associated histopathology identified variable white matter injury with patchy deposition of amyloid precursor protein (APP), loss of neurofilament-positive axonal processes, myelin dissolution, astrogliosis, microgliosis, and perivascular hemosiderin-laden macrophages. Multiple linear regression revealed that tract disruption strongly correlated with the density of APP-positive axonal swellings and neurofilament loss. Ex vivo diffusion MRI can detect tract disruptions in the human brain that reflect axonal injury