Somatic condition, growth and distribution of Atlantic bluefin tuna (Thunnus thynnus) in the Gulf of Maine

Atlantic bluefin tuna (Thunnus thynnus), a highly migratory apex predator, utilize temperate feeding grounds to place their tissues into positive lipid balance following reproduction and subsequent migration to northern latitudes. Commercial fishermen target Atlantic bluefin tuna between June and October, but landings have declined 70% from 2004-2009 suggesting adult bluefin tuna may no longer be utilizing the Gulf of Maine as a foraging ground. A series of linear and additive models fitted to multiple fishery dependent datasets identified significant declines in the somatic condition of Atlantic bluefin tuna in the Gulf of Maine. Significant changes in the somatic condition of Atlantic herring, increases in the landings of the commercial herring fleet and changes in Atlantic herring gonad size were also identified. New growth parameters were estimated for Atlantic bluefin tuna sampled in the western Atlantic and these are significantly different than previous estimates for bluefin tuna greater than eight years of age. Finally, there has been a significant shift in the distribution of Atlantic bluefin tuna surface schools greater than 350 kilometers to the east over the past 28 years. Significant associations between Atlantic bluefin tuna and Atlantic herring schools were also identified, but long-term shifts in Atlantic herring distributions did not follow the same trend as Atlantic bluefin tuna. These results suggest bottom-up and top-down mechanisms are responsible for the changes in somatic condition and distribution of Atlantic bluefin tuna in the Gulf of Maine

Decline in condition of northern bluefin tuna (Thunnus thynnus) in the Gulf of Maine

The northern bluefin tuna (Thunnus thynnus) is a highly mobile apex predator in the Gulf of Maine. Despite current stock assessments that indicate historically high abundance of its main prey, Atlantic herring (Clupea harengus), commercial fishermen have observed declines in the somatic condition of northern bluefin tuna during the last decade. We examined this claim by reviewing detailed logbooks of northern bluefin tuna condition from a local fishermen’s cooperative and applying multinomial regression, a robust tool for exploring how a categorical variable may be related to other variables of interest. The data set contained >3082 observations of condition (fat and oil content and fish shape) from fish landed between 1991 and 2004. Energy from stored lipids is used for migration and reproduction; therefore a reduction in energy acquisition on bluefin tuna feeding grounds could diminish allocations to growth and gamete production and have detrimental consequences for rebuilding the western Atlantic population. A decline in northern bluefin tuna somatic condition could indicate substantial changes in the bottom-up transfer of energy in the Gulf of Maine, shifts in their reproductive or migratory patterns, impacts of fishing pressure, or synergistic effects from multiple causes

Correction: Atlantic Bluefin Tuna (Thunnus thynnus) Biometrics and Condition

Correction: Atlantic Bluefin Tuna (Thunnus thynnus) Biometrics and ConditionPostprint4,411

Atlantic Bluefin Tuna (Thunnus thynnus) Biometrics and Condition

The compiled data for this study represents the first Atlantic and Mediterranean-wide effort to pool all available biometric data for Atlantic bluefin tuna (Thunnus thynnus) with the collaboration of many countries and scientific groups. Biometric relationships were based on an extensive sampling (over 140,000 fish sampled), covering most of the fishing areas for this species in the North Atlantic Ocean and Mediterranean Sea. Sensitivity analyses were carried out to evaluate the representativeness of sampling and explore the most adequate procedure to fit the weight-length relationship (WLR). The selected model for the WLRs by stock included standardized data series (common measurement types) weighted by the inverse variability. There was little difference between annual stock-specific round weight-straight fork length relationships, with an overall difference of 6% in weight. The predicted weight by month was estimated as an additional component in the exponent of the weight-length function. The analyses of monthly variations of fish condition by stock, maturity state and geographic area reflect annual cycles of spawning and feeding behavior. We update and improve upon the biometric relationships for bluefin currently used by the International Commission for the Conservation of Atlantic Tunas, by incorporating substantially larger datasets than ever previously compiled, providing complete documentation of sources and employing robust statistical fitting.WLRs and other conversion factors estimated in this study differ from the ones used in previous bluefin stock assessments.Postprint4,411

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

Despite current guidelines, intraperitoneal drain placement after elective colorectal surgery remains widespread. Drains were not associated with earlier detection of intraperitoneal collections, but were associated with prolonged hospital stay and increased risk of surgical-site infections.Background Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice. Methods COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien-Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement. Results Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P < 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P < 0.001). Conclusion Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk

Use of ultrasonic telemetry to determine the area of bait influence and trapping area of American lobster, Homarus americanus, traps

Using ultrasonic telemetry, we measured the distance of attraction to a baited trap and then used this value to calculate the “area of bait influence”. This value, along with the mean daily home range for the same animals, was used to calculate the “trapping area” of an individual trap. Lobsters (n = 25) were tracked inside a large underwater mesocosm containing a single baited lobster trap. During the study, 14 of the 25 lobsters approached the trap from a mean (+SEM) distance of 11.0 ± 0.7 m. Using this distance as the radius of a circle, the resulting circular area of bait influence was 380 m2. The movements of 18 lobsters were used to calculate a mean daily home range of 1002.4 ± 195.7 m2. The radius of a circle with this area (17.8 m) was then combined with the mean distance of bait attraction to calculate the trapping area, defined as: the total area from which the catch is drawn (2604.0 m2; a circle with a radius of 28.8 m or 17.8 m + 11.0 m). A demonstration of the potential use of empirical data about lobster home ranges, trap dynamics and area of bait influence to improve our understanding of the relationship between the density of lobsters on the bottom and catch is included

Home range dynamics of the American lobster, Homarus americanus

A fixed array ultrasonic telemetry system was used to track the fine scale movements of American lobsters, Homarus americanus, within a large enclosure (mesocosm, 3125 m2). Positions of lobsters were obtained continuously, at 5 min intervals, for an average of 4.1 days. A kernel method was used to estimate the daily home ranges (95% utilization distribution, UD), core areas of activity (50% UD) and distance traveled by each lobster. The mean home range size for all lobsters was 760.1 ± 132.0 m2 (n = 32), and the average core area was 74.0 ± 10.9 m2. Home range size was closely correlated with the daily distance traveled by lobsters (523.2 ± 78.1 m day−1; r 2 = 0.62, p = 0.0001). Within the size range of lobsters used in this study (62–93 mm carapace length), there was no correlation between the lobster sizes and the areas of their home ranges. Lobsters changed core areas and home ranges often, occupying 1.4 ± 0.1 different core areas each day. However, despite changing their core areas, the size of their home ranges remained fairly consistent from one day to the next. These data illustrate both the residential and the nomadic nature of lobster movements and demonstrate the utility of fixed array ultrasonic telemetry for quantifying the fine-scale movements of lobsters

Daily patterns of locomotion expressed by American lobsters (Homarus americanus) in their natural habitat

The local movements and activity patterns of American lobsters, Homarus americanus, were monitored inside a 50 m by 50 m underwater enclosure (mesocosm) using ultrasonic telemetry. Forty-four lobsters of both sexes, ranging in size from 62 to 93 mm in carapace length, were continuously tracked for 2-10 days in 2002 and 2003. As a population, the movement rate of lobsters depended on time of day, as defined by dawn, day, dusk or night. Lobster movement rates were significantly higher during night and dawn than day and dusk hours. Movement rates did not differ by lobster sex, size or between years of the study. The effect of time of day differed between lobsters, and there was considerable variability in the time of day when individual lobsters were most active. Thirty lobsters moved significantly more during the night, five moved significantly more during the day, and nine did not move significantly more during the day or night. Therefore, while there was a general tendency for lobsters in this study to be more active at night, certain factors in their natural habitat modulated this nocturnal bias, which led to a tremendous amount of variability in their daily patterns of behavior