Chronic neurophysiology studies in Rhesus macaques (Macaca mulatta) require implantation of cranial hardware including headposts, recording chambers, and fixation screws. A common complication is persistent picking, scratching and grooming around implant margins, which can result in skin retraction, chronic inflammation, infection, repeated surgical repairs, and premature removal of the animal from research studies. Existing implant-care protocols rely heavily on topical therapies that may inadvertently increase grooming behavior. We developed a removable carbon fiber 3D-printed cranial cap that attaches directly to the headpost, covering the implant margins while allowing airflow and rapid removal during recording sessions. Three macaques received the protective 3D-printed cap. One animal tolerated the device for 836 days, during which implant manipulation ceased, surgical repair frequency decreased, and an additional 1056 h of electrophysiological data were collected. A second animal successfully used the 3D-printed cap during postoperative healing for 61 days following implant revision surgery. One animal did not tolerate the 3D-printed cap, and it was removed. This case study suggests that a simple, low-cost 3D-printed cap has the potential to improve wound healing, reduce implant manipulation, enhance animal welfare, and prolong the functional lifespan of chronic cranial implants in appropriately selected animals.
Prostatitis is one of the most common prostatic disorders in dogs, although its ultrasonographic features remain poorly characterized. The aim of this retrospective study was to describe the ultrasonographic findings of canine prostatitis and prostatic abscessation and to investigate their association with clinical and laboratory abnormalities. Medical records of 35 client-owned dogs with cytologically or histologically confirmed acute prostatitis were reviewed. Clinical, ultrasonographic, laboratory, bacteriological, treatment, and follow-up data were collected. The most common ultrasonographic findings were inhomogeneous parenchymal echotexture, intraparenchymal cystic lesions, capsular edema, periprostatic steatitis, and asymmetry of the prostatic lobes. Prostatic abscesses were detected in 25 dogs and showed marked variability in size and morphology. Abscess diameter was positively correlated with body weight (p = 0.001; rho = 0.6) and negatively correlated with the percentage of neutrophils with toxic granulation (p = 0.02; rho = −0.4). Most dogs recovered following medical or combined medical–surgical treatment. Follow-up examinations demonstrated resolution of the inflammatory changes surrounding the prostate, whereas parenchymal inhomogeneous echotexture frequently persisted. These findings provide a comprehensive ultrasonographic description of canine prostatitis and support the use of ultrasonography as a valuable tool for diagnosis and follow-up.
Wetlands support fisheries and other livelihoods but can also bring people into close contact with crocodilians. Human–crocodile conflict has been documented across Africa, Asia, Australia and the Americas, yet indirect economic costs, including damage to fishing gear, remain less studied than attacks on people or livestock. We analysed questionnaire data from 379 respondents in purposively selected crocodile-exposed fishing communities in the southern Sudd Wetlands, South Sudan. The study quantified seasonal patterns of Nile crocodile (Crocodylus niloticus) damage to fishing gear, reporting pathways, conflict-resolution perceptions, responses to damaged gear and likely annual damaged-net categories. Reporting pathways were defined as the social and institutional channels through which respondents said gear-damage incidents were communicated; handling responses were defined as actions taken after gear was damaged. As expected from seasonal variation in floodplain use, the water level and fishing activity, reported damage was concentrated from July to December, with September the being most frequently selected main damage month (157 respondents; 41.4%). Quarterly ordinal responses differed among seasons (Friedman test: χ2=721.54, df = 3, p<0.001). Cumulative link models that included both quarters and the broader survey area showed the largest odds-ratio contrasts for July–September and October–December, whereas broader-area contrasts were smaller, and their confidence intervals overlapped one. Reporting was dominated by informal and community pathways: fishing-camp leadership, family members and other fishers each reached 100% agreement, whereas wildlife authorities received no affirmative reporting. Respondents also expressed little confidence in formal conflict resolution: 100% agreed that crocodile-related gear-damage conflicts were difficult to resolve, and 0% agreed that government would compensate for damaged gear. Damaged nets were mainly abandoned and replaced; repair was rare (1.6%). The most likely annual damaged-net category was 1–5 nets/year/participant (275 respondents; 72.6%). Because the survey was purposive, the results should be interpreted as patterns among sampled respondents and locations, not as prevalence estimates for all fishers in the Sudd Wetlands or South Sudan. The findings indicate that seasonal gear damage, weak formal reporting to wildlife institutions and limited institutional confidence should be central considerations in crocodile-conflict management.
The tri-spine horseshoe crab, Tachypleus tridentatus, is an evolutionarily ancient marine chelicerate of considerable ecological and conservation importance in the Indo-West Pacific. Although several mitochondrial genomes have been reported, comprehensive comparative mitogenomic analyses encompassing all extant limulid genera remain limited. In this study, we sequenced and characterized the complete mitochondrial genome of an F1 Tachypleus tridentatus individual derived from wild-caught broodstock from the Beibu Gulf, northern South China Sea, and subsequently maintained at an aquaculture facility, using high-throughput sequencing, and performed an integrated comparative mitogenomic analysis across the three extant genera of Limulidae. The circular mitochondrial genome was 15,006 bp in length and contained the typical set of 37 mitochondrial genes, including 13 protein-coding genes (PCGs), 22 transfer RNA genes, and two ribosomal RNA genes. The newly sequenced Tachypleus tridentatus mitogenome showed highly conserved genome organization and nucleotide composition relative to previously published conspecific mitogenomes, confirming established mitochondrial characteristics of the species. The principal contribution of this study is the addition of a complete Beibu Gulf mitogenome and its integration with 12 additional complete mitochondrial genomes representing all extant limulid species, together with four mitochondrial markers, K2P genetic-distance analyses, and independent BI and ML phylogenetic reconstruction. The concordance among these mitochondrial datasets provides an integrated assessment of genetic divergence and mitochondrial phylogenetic relationships within Limulidae and expands the geographic representation of complete mitochondrial genomic resources for Tachypleus tridentatus.
This prospective, randomised, ex vivo study investigated the effects of manual double-spin centrifugation protocols on the cellular and growth factor composition of equine platelet-rich plasma (PRP). Blood from 20 healthy horses was evaluated in two phases. In Phase A (n = 10), nine first-spin protocols were compared, and two were selected based on platelet enrichment and leukocyte reduction. In Phase B (n = 10), these were combined with nine second-spin conditions, generating 18 PRP preparations. Platelet (PLT), leukocyte (WBC) and erythrocyte (RBC) concentrations and PDGF-BB and TGF-β1 concentrations were measured. No significant differences in cellular composition were identified among first-spin protocols (p > 0.05). From Phase B, all final preparations achieved platelet enrichment and leukocyte depletion, with negligible RBC contamination. Second-spin force significantly affected PDGF-BB and TGF-β1 concentrations (p < 0.001). PDGF-BB increased from 2629 pg/mL (95% CI: 2111–3274) at 200× g to 3467 pg/mL (95% CI: 2784–4317) at 1000× g, while TGF-β1 increased from 13,364 pg/mL (95% CI: 11,286–15,824) to 16,998 pg/mL (95% CI: 14,355–20,127). TGF-β1 also increased with second-spin duration (p = 0.01). Platelet concentration was positively correlated with PDGF-BB (ρ = 0.604) and TGF-β1 (ρ = 0.691; both p < 0.001), whereas WBC concentration showed no significant association with either growth factor. Thus, both preparation methodology and donor-related variability influence equine PRP composition, indicating that protocol standardisation alone is unlikely to ensure biologically consistent PRP products.
This study investigated the effects of short periods of incubation during egg storage (SPIDES) on egg quality, hatching performance, and chick quality in Alectoris chukar eggs subjected to extended storage durations. A total of 800 eggs collected from a 60-week-old chukar partridge breeder flock were allocated to eight experimental subgroups in a 4 × 2 factorial design, with storage period (35, 42, 49, and 56 days) and treatment (control or SPIDES) as the main factors (100 eggs/subgroup). All eggs were stored at 9–12 °C and 75% relative humidity in a pointed-end-up position with 24 rotations per day for their assigned storage duration (35, 42, 49, or 56 days). In the SPIDES groups, eggs were incubated for 2 h at 37.7 °C and 59% relative humidity in 7-day intervals, commencing on day 28 of storage. As storage duration increased, Haugh unit, albumen index, and yolk index decreased significantly (p < 0.001), while yolk ratio (p < 0.05) and yolk-to-albumen ratio (p < 0.01) increased. The overall hatchability decreased at 49 and 56 days of storage, while the hatchability of fertile eggs was lowest at 56 days (p < 0.05). Early embryonic mortality increased significantly at 56 days of storage (p < 0.05). SPIDES had a limited effect on most egg quality traits, including Haugh unit, albumen index, and egg component weights, but significantly improved the hatchability and hatchability rate of fertile eggs, reduced early embryonic mortality, and enhanced the overall chick quality score (p < 0.05). These findings indicate that chukar partridge eggs exhibit considerable resistance to long-term storage; however, SPIDES represents a beneficial management strategy for maintaining embryonic viability when storage duration exceeds practical limits.
This study investigated the effects of dietary nano-selenium (nano-Se) levels and Se sources on growth performance, blood parameters, meat quality, and tissue Se deposition in broilers. In Experiment 1, 480 broilers were assigned to five treatments (0, 0.10, 0.20, 0.30, and 0.40 mg/kg nano-Se) to assess the dose-dependent effects of nano-Se, with 0.20–0.22 mg/kg identified as the optimal dose through quadratic regression. In Experiment 2, 480 broilers received either a control diet or diets supplemented with 0.20 mg/kg Se from nano-Se, sodium selenite (SS), or two organic Se sources (Se-enriched yeast 1 and 2, SY1 and SY2). Supplementation with 0.20–0.30 mg/kg nano-Se improved (p < 0.05) antioxidant status, carcass yield, muscle redness at 45 min post-slaughter, and Se concentration in serum. At 0.20 mg/kg, nano-Se, SY1, and SY2 showed greater improvements in carcass traits, and antioxidant status than SS (p < 0.05), with comparable efficacy between nano-Se and organic sources. Nano-Se, organic Se sources, and SS increased Se deposition in serum and breast muscle compared to the control (p < 0.05). In conclusion, 0.20 mg/kg nano-Se is recommended for broiler diets, demonstrating superior bioefficacy to inorganic Se and comparable effects to organic Se sources.
Sebastes schlegelii is a commercially significant species in the northern Yellow Sea. Recently, Sebastes schlegelii has shown a reduced stock density and a shift toward smaller body sizes in the northern Yellow Sea area off Liaoning Province. To comprehend the population dynamics and to formulate management tactics, we established a mathematical formula describing the length–weight relationship, as well as the corresponding growth equations for the body length and body weight. The biomass of Sebastes schlegelii in the northern Yellow Sea area off Liaoning Province was evaluated using biological survey data from 2019 to 2022. The findings reveal that the length–weight formula is expressed as W = 4.98 × 10−5L2.8878 (R2 = 0.9108), with L∞ = 407.6 mm, W∞ = 1717.04 g, K = 0.21 a−1, and t0 = −0.65 a. The critical age was 3.34 years, and the stock biomass was 13,141.35 tonnes. The current exploitation rate of this resource is below the maximum yield, indicating sustainable utilization. A fishing closure period from April to June is considered suitable. A minimum landing size of 240.48 mm is recommended for Sebastes schlegelii.
Hydropower regulation can alter riverine habitats and potentially influence fish diet, gut microbiota, and nutritional characteristics. In this study, upstream and downstream populations of Hemibagrus guttatus (H. guttatus) were investigated in a dam-regulated reach of the Hongshui River associated with the Datengxia Water Conservancy Project using 12S rRNA and COI metabarcoding, 16S rRNA gene sequencing, and muscle nutritional analyses. Fish from the two habitats exhibited distinct dietary compositions, accompanied by significant differences in gut microbial diversity, community structure, and predicted microbial functions. Upstream fish harbored higher microbial diversity and greater abundances of Firmicutes-associated taxa, including several putatively beneficial bacteria, whereas downstream fish showed enrichment of Proteobacteria-associated taxa and functions related to environmental adaptation. Muscle composition also differed between habitats, with upstream fish containing higher moisture and crude lipid contents and downstream fish exhibiting higher crude protein content. These habitat-associated differences suggest that natural dietary resources and intestinal microbiota are closely linked to host nutritional characteristics. These findings highlight the importance of considering upstream–downstream habitat origin when evaluating the trophic, microbial, and nutritional characteristics of H. guttatus and provide a biological reference for the management and conservation of fish populations in dam-regulated rivers.
Canine degenerative myelopathy (DM) is a progressive, adult-onset neurodegenerative disease, with similarities to superoxide dismutase 1 (SOD1)-associated ALS. Clinical signs of DM begin with asymmetric pelvic limb general proprioceptive ataxia and spastic paresis that progresses to flaccid tetraplegia and respiratory failure. Although pelvic limb muscle atrophy and peripheral neuropathy have been reported in DM, intramuscular SOD1 accumulation and muscle spindle pathology remain incompletely characterized. This study evaluated pathological changes in the tibialis cranialis muscle of Pembroke Welsh Corgis with early- and late-stage DM and age-matched unaffected controls. Histologic stains and immunohistochemistry were used to evaluate myofiber morphology, fiber type distribution, muscle spindle integrity, and SOD1 immunoreactivity. Compared to unaffected dogs, DM-affected dogs exhibited increased SOD1 immunolabeling, greater variability in myofiber size, altered myofiber shape and packing, and fibrosis. A progressive reduction in the percentage of type I myofibers was observed without evidence of fiber type grouping. These changes were evident during early disease and became more pronounced with disease progression. Muscle spindles exhibited late-stage disruption of intrafusal myofiber organization and marked increase in SOD1 immunoreactivty. The observed alterations suggest that the muscle pathology was, at least in part, intrinsic to the muscle, rather than being secondary to neurodegeneration. Our findings demonstrate early and progressive pathological changes in the tibialis cranialis muscle, expanding our understanding of skeletal muscle involvement in DM.
Nationally, there is a growing population of shelter dogs that are experiencing longer lengths of stay as euthanasia rates decline. Well-documented shelter-specific stressors can induce physiological and behavioral changes correlated with immediate and future welfare concerns. Dogs vary in their responses to the shelter environment based on genetics, past experiences, and context, leaving some individuals unable to adapt. Those that struggle may display maladaptive coping behaviors perceived as less desirable by adopters, perpetuating the stress response cycle. To address welfare concerns, behavioral interventions, including enrichment and training programs, may mitigate stress; however, there remains a population that could benefit from pharmaceutical interventions by supporting individuals at a physiological level. Shelter resources vary significantly, and differences in training, experience, and clinical staff can create challenges to accessing anxiolytic medications. Most shelter behavior assessments focus on temperament testing to predict future behavior at home or identify individuals at risk for aggression, but few exist that can help identify generalized stress related to their current environment. There remains a need for a validated behavior assessment that measures coping ability in a clinically meaningful way to facilitate partnerships between shelters and veterinarians, addressing immediate shelter dog welfare concerns.
Proteomics, the study of the structure and function of proteins, has been used to investigate candidate biomarkers and study the pathophysiology of various diseases. Biomarkers may be useful in diagnosing, monitoring and assessing treatment responses. This review provides an overview of proteomic techniques, describes the workflow and pipeline for biomarker discovery, and evaluates the current literature on proteomic studies in veterinary gastroenterology in dogs and cats. Current studies in this field are advancing our understanding of disease pathophysiology in conditions such as chronic enteropathy (CE). For biomarker development, proteomic research in veterinary gastroenterology is still in the early discovery phase. Substantial work on verification and validation is required before proteomic biomarkers can be reliably translated into clinical practice in companion animals.
This study aimed to determine the apparent metabolizable energy (AME), nitrogen-corrected AME (AMEn), and net energy (NE) values of corn for Arbor Acres (AA) broilers aged 12–14 and 26–28 days and to develop prediction equations. Ten corn samples with varying chemical compositions were selected. Test diets were formulated using the substitution method, in which corn replaced 40% of the energy-supplying components in a basal diet. A total of 396 male AA broilers at 9 days of age and another 396 at 23 days of age were used across the two metabolism trials. AME, AMEn and NE were determined using the substitution method combined with respiratory calorimetry. Correlations between energy values and chemical components were analyzed. Multiple linear stepwise regression in SPSS was used to establish prediction equations for AME, AMEn, and NE. The results showed that for 12–14-day-old broilers, AME, AMEn, and NE ranged from 13.84–15.66 MJ/kg, 13.39–15.35 MJ/kg, and 8.61–12.56 MJ/kg, respectively. For 26–28-day-old broilers, the corresponding values ranged from 14.62–16.30 MJ/kg, 14.42–16.05 MJ/kg, and 10.42–13.06 MJ/kg. Notably, NE values and AME/GE (gross energy) ratios were significantly higher in 26–28-day-old broilers than in 12–14-day-old broilers (p < 0.05), which increased by 9.33% and 3.96%, respectively. Correlation analysis showed that phytic acid (PA) was significantly negatively correlated with AME, AMEn, NE, AME/GE, and AMEn/GE in the younger group, whereas ash content was significantly negatively correlated with AME and AMEn in the older group. The prediction equations exhibited good fit, with the coefficient of determination (R2) of the best equation reached 0.97. These findings support the precise application of corn in feed formulation and provide a scientific basis for its efficient utilization in poultry production.
Apostichopus japonicus is a temperate marine echinoderm whose growth and reproduction are strongly influenced by temperature. We compared adult sea cucumbers exposed to stepwise warming (10–12, 12–14, and 14–16 °C across three successive 20-day stages) with animals maintained at 15 °C. Growth indices, gonadosomatic index (GSI), gonadal histology, and energy-budget components were evaluated in females and males. The 60 d experiment used three replicate tanks for each treatment-by-sex combination. Compared with the constant 15 °C treatment, the stepwise-warming regime showed a higher female GSI at stage III; representative gonadal sections documented stage-related structural changes in both treatments. No significant treatment effects were detected for final wet weight, specific growth rate, daily growth rate, or feed conversion ratio. Excretory energy decreased during stages II and III, while the proportion allocated to gonadal growth increased. Stage-specific within-sex comparisons showed higher gonadal growth energy under stepwise warming in both sexes during stage II, while the clearest GSI difference occurred in females during stage III; treatment × sex interactions were not significant. The clearest differences between the two temperature regimes were observed during stages II and III (12–16 °C). The findings provide an integrative physiological basis for temperature management during broodstock conditioning of A. japonicus.
Morphometric information on ambling horses raised in Türkiye remains limited. This study aimed to characterize the morphometric traits of ambling horses according to breeding origin, age, and sex and to provide baseline phenotypic information on the studied population. A total of 102 naturally ambling horses were evaluated, including indigenous horses raised in Bursa (n = 28), indigenous horses raised in Nazilli, Aydın Province (n = 65), and Afghan-origin horses raised in Bursa (n = 9). Morphometric measurements of the head, body, and limbs were recorded, and the effects of breeding origin, age, and sex were analyzed using a general linear model. Significant differences among breeding origins were observed for several morphometric traits (p < 0.05). Afghan-origin horses generally exhibited higher values for several body measurements, particularly withers height, body length, chest depth, chest width, and heart girth, reflecting morphometric differences within the studied sample. Age- and sex-related differences were also observed for several morphometric traits. The strongest correlation was observed between CH and BH (r = 0.920, p < 0.001), followed by WH and BH (r = 0.873, p < 0.001) and WH and CH (r = 0.860, p < 0.001). ITH was also positively correlated with BH (r = 0.825), CH (r = 0.808), and WH (r = 0.744) (all p < 0.001). Overall, this study provides baseline morphometric information on ambling horses from different breeding origins raised in Türkiye and contributes to the phenotypic characterization of the studied population. However, because the Afghan-origin group included only nine horses and the distribution of animals among some groups was unbalanced, the observed differences should be interpreted with caution. Further studies involving larger and more balanced populations are needed to confirm these findings.
Pastoralist communities in Karamoja maintain close, multifaceted relationships with animals from early childhood, yet little is known about how children conceptualise animal emotions and cognitive abilities. This pilot study explored these conceptions among Kasimeri Primary School students in Karamoja, Uganda, within the AICS All-In-One Project (AID 012590/04/1). A cross-sectional survey was conducted using a structured questionnaire administered to 326 students (mean age 13 ± 2 years). Data were analysed using descriptive statistics and generalised linear models (GLMs). Most children attributed a wide range of emotions to animals, with anger (79.6%) and happiness (78.2%) being the most widely recognised and disgust the least attributed (63.2%). Emotion ascription differed significantly by emotion type (p < 0.001) and species (p = 0.004), with significant interactions (p = 0.022). Species differences emerged for several emotions (all p ≤ 0.006), with ruminants and chickens receiving higher attribution than dogs, reflecting different species’ roles in pastoral life. Students from pastoralist households showed lower emotion scores than those with non-farmer fathers (p = 0.025). Cognitive ability attribution also differed significantly across species (all p < 0.001). These findings challenge Western-pet-centred frameworks, highlighting the need for culturally grounded, One Health-oriented educational approaches integrating local animal knowledge with formal welfare and health curricula.
Chironomids are abundant aquatic macroinvertebrates with known pollutant tolerance, but the molecular effects of chlorantraniliprole (CAP) remain unclear. In this study, we exposed Propsilocerus akamusi larvae to LC10 and LC50 of CAP, sampled at 48 h and 144 h, and integrated biochemical assays, metabolomics, and transcriptomics to profile stress responses. Our results showed that CAP elevated antioxidant enzymes and protein carbonyls, indicating severe oxidation, especially at LC50. At 48 h, LC10 activated JNK-mediated antioxidative and drug metabolism pathways, whereas LC50 altered glycolysis, cofactor biosynthesis, and fatty acid metabolism. At 144 h, LC10 enriched proteasome and oxidative phosphorylation pathways; chaperones PaHsp70 and PaHsp90 were upregulated by 4.14- and 2.08-fold, respectively, and were negatively correlated with lipid and carbohydrate metabolites, indicating a metabolic shift toward protein repair. In contrast, LC50 CAP triggered protein processing in the endoplasmic reticulum (ER) and TCA cycle dysregulation, with upregulation of PaCalreticulin linked to energy crisis markers, reflecting severe energy collapse. After knockdown of PaHsp70, the survival rates of chironomid larvae exposed to LC10 and LC50 CAP significantly decreased from 80.8% to 65.8% and from 43.3% to 28.3%, respectively. Collectively, our results revealed that low CAP concentrations triggered early detoxification followed by proteasome- and Hsp-mediated strategies to sustain protein homeostasis whereas high concentrations directly disrupted core metabolism and ultimately caused energy collapse and lethal ER stress in chironomid larvae. These findings provide mechanistic insights into the chronic effects of CAP on aquatic insects.
Weaning stress and antinutritional components in conventional soybean meal may impair intestinal homeostasis and growth in nursery piglets. This study compared five soybean protein sources: conventional soybean meal (SBM), rapidly expanded soybean meal (RSB), fermented soybean meal (FSBM), hydrolyzed soybean protein (HP), and extruded full-fat soybean (ESB). Two concurrent 28-day trials used 120 newly weaned piglets, with 60 piglets per trial allocated to five treatments (six pens per treatment and two piglets per pen): a single-diet trial and a dual-choice feed-preference trial. Growth, feed preference, crude protein digestibility, serum biomarkers, and colonic microbiota were evaluated. HP showed the highest in vitro and apparent crude protein digestibility and increased final body weight and average daily gain relative to SBM and RSB (p < 0.05). Compared with SBM, HP increased serum IgA, IL-2, GH, and IGF-1 and decreased TNF-α (p < 0.05). Serum antioxidant indices and microbial alpha diversity did not differ among treatments (p > 0.05). Descriptive genus-level analyses indicated a higher relative abundance of Lactobacillus in the HP and FSBM groups. Overall, HP produced the most consistent improvements in protein digestibility and selected growth and serum outcomes under the conditions of this study.
Free-ranging pet cats have been identified as significant predators of wildlife. Managing this conflict is challenging, because control of movement ultimately lies with the owner. Previous research has focused on the influence of environmental, intrinsic, husbandry-, and personality-related factors on cats’ behavior when stepping out the door. However, an overlooked driver is the strength of the cat–owner relationship. In this explorative study, we used animal-borne video cameras to document the outdoor behavior of 12 cats and in parallel assessed the relationship with their owners through the Cat–Owner Relationship Scale (CORS), along with intrinsic (age and sex) and husbandry-related (cat’s role, cat’s restriction and roaming pattern, parasite treatment, and provisioning households) determinants. We found no statistical evidence of a direct influence of the cat–owner relationship on exploratory and hunting behaviors, but owners with higher CORS scores observed more harassment incidents by their cats and owners reporting more hunting behavior tended to own cats that roamed more in nature; those cats also explored more. We further observed high individual variability in hunting and time allocated to urban and natural environments. Comparing our results with the previous literature, we conclude that outdoor behavior largely varies between individual cats and is difficult to predict. However, the greater awareness of cat–wildlife conflict among owners with stronger bonds may provide an opportunity to promote changes in owner behavior.
Understanding habitat suitability and environmental preferences of shortbill spearfish (Tetrapturus angustirostris) is essential for assessing and mitigating bycatch risk in pelagic longline fisheries. Using observer data collected by the Chinese Pacific tuna longline fishery, including 19,932 longline sets collected during 2010–2021, we compared five individual modelling algorithms and three ensemble strategies to predict habitat suitability across the Pacific Ocean and identify key environmental drivers. Model performance was evaluated using repeated 10-fold cross-validation with three repetitions. The stacking ensemble achieved the highest predictive performance (AUC = 0.872; TSS = 0.591), followed closely by random forest (RF; AUC = 0.869), although the absolute difference between these two models was small. A sensitivity analysis including log-transformed observed hooks resulted in only minor improvements in RF and stacking performance and did not materially alter the main habitat-suitability patterns. Both generally outperformed the other individual and weighted ensemble models. Permutation-based importance analyses consistently identified salinity as the strongest environmental predictor of habitat suitability, followed by chlorophyll-a concentration, distance to shore, and dissolved oxygen concentration. Partial dependence analyses showed that the stacking ensemble produced smoother and more readily interpretable responses to environmental gradients, particularly salinity and dissolved oxygen, whereas RF placed greater importance on a limited number of dominant predictors. Highly suitable habitat was primarily predicted in subtropical offshore waters of the southeastern Pacific (10° S–25° S, 100° W–130° W), which were characterized by relatively high salinity, moderate dissolved oxygen concentrations, and low chlorophyll-a concentrations. A secondary area of elevated suitability was identified in the central North Pacific (160° E–180° E, 15° N–25° N). Overall, the stacking ensemble provided robust predictions of shortbill spearfish habitat suitability, whereas RF remained useful for identifying dominant environmental correlates. The predicted habitat maps provide a spatial basis for identifying potential bycatch-risk hotspots and supporting adaptive management strategies, such as spatially targeted monitoring and mitigation measures in tuna longline fisheries.
