Harvest Year Research Articles

Pesticide residue levels in strawberries and human health risk assessment

Pesticides have been a primary tool in pest management worldwide. However, pesticide contamination is a major food safety risk in the fresh food supply chain. This study aims to monitor 240 pesticide residues in 245 strawberry samples and assess the health risk for Turkish adult and child consumer groups. Over three consecutive harvest years (2021–2023), strawberries were collected from farmers in the Aydın region of Turkey and analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Out of the 245 strawberry samples analysed, 61.6 % contained 32 different pesticides (17 fungicides and 15 insecticides), five of which were non-approved. Additionally, 6.5 % of the strawberry samples exceeded the European Union Maximum Residue Limits (MRLs). Multiple residues were recorded in 42.9 % of strawberry samples. Pyrimethanil was the most commonly identified pesticide (30.2 %), followed by boscalid (27.4 %), fluopyram (17.1 %), and bifenazate (15.1 %). In the worst-case scenario, cumulative exposure to pesticides through strawberry consumption was determined to be 6.5 × 10⁻⁵ mg kg⁻¹ b.w. day⁻¹ for adults and 2.0 × 10⁻⁴ mg kg⁻¹ b.w. day⁻¹ for children. The hazard index (HI) values, under the worst-case scenario, were calculated to be 0.32 % for adults and 0.97 % for children. These results indicate that there is no cause for concern regarding cumulative exposure to residues through strawberry consumption for the Turkish population.

Influence of Terroir on the Grain Composition, and Volatile Profile of Irish Grain (Wheat) New Make Spirit

Terroir refers to the combination of environmental factors, such as climate, soil, and agricultural practices, that shape the characteristics of a crop, contributing to the unique qualities of the final product. The concept has been traditionally linked to wine, but some recent findings suggest that it also holds importance for distilled spirits. The expanding Irish distilling sector is shifting towards local raw materials such as wheat and rye, driven by regulatory changes, economic benefits, and consumer demand for sustainable local products. This research examines the effects of wheat variety, geographical location, and harvest year on grain composition and volatile composition of the new make spirit. For this study, twenty lab-scale wheat whiskey samples were produced from five different wheat varieties grown at two different locations in Ireland over two consecutive years. The wheat samples were analysed for grain composition and the volatile profiling of new make spirit samples by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC-MS). A total of fifty-one volatile compounds were detected, with ethanol, ethyl acetate, phenyl ethyl alcohol, and 3-methyl-1-butanol being predominant. Principal component analysis revealed that both the harvest year and geographical location moderately influenced the volatile compound distribution of the new make spirit, which is explained by a 43.25% variance. ANOVA analysis revealed that grain composition was significantly influenced by harvest year, location, and wheat variety. The 2020 samples showed higher protein and β-glucan content, whereas samples from the location Tipperary had higher starch content. This study indicates that terroir—specifically seasons (year) and geography (location)—affects the characteristics of wheat-based Irish whiskey, highlighting opportunities for distillers to differentiate their products by leveraging local environmental factors.

Optimizing geographical traceability models of Chinese Lycium barbarum: Investigating effects of region, cultivar, and harvest year on nutrients, bioactives, elements and stable isotope composition

Lycium barbarum is a type of “medicine-food homology” whose geographical origin has attracted strong interest from consumers due to different regional quality characteristics. A sophisticated OPLS-DA model to verify Lycium barbarum origin was developed using 266 samples gathered from five cultivars in two regions between 2020 and 2022, which was based on 67 indices, including nutrients, bioactives, elements and stable isotopes. Twelve variables (fructose, δ2H, glucose, tartaric acid, Mo, Na, Sr, His, Phe, Mn, Lys and Rb) were selected to refine models that could distinguish Lycium barbarum origin without being impacted by cultivar or year. The model of training set and testing set samples had discrimination rates of 100 % and 94.71 % to 98.28 %, suggesting an optimized multi-variate analysis strategy using OPLS-DA model could correctly predict the origin of blind Lycium barbarum samples. This study provides new evidence for constructing a reliable traceability model for the geographical origins of Lycium barbarum.

Impacts of Harvest Year and Cultivation Location on Off-Flavor Compounds and Functionality of Pea Protein Isolate.

The impact of four different harvest years and two cultivation locations (CLs) of pea seeds on their protein wet fractionation yield, volatile and non-volatile beany flavors, and functionality were investigated. Both harvest years and CLs significantly affected protein recovery, but protein purity was primarily influenced by CLs. Seed age emerged as a dominant factor causing the reduction in linolenic/linoleic acid content and lipoxygenase (LOX) activity which surpassed the effect of harvest years in the seeds but not in their proteins. CL significantly affected fatty acid composition in both seeds and proteins, whereas its effect on LOX activity was discernible only in the proteins. Volatile beany compounds in the proteins were affected by both harvest years and CLs, correlating with their polyunsaturated fatty acid (PUFA) content and LOX activity. Both factors minimally impacted the emulsification capacity of the proteins but imposed a significant effect on their rheological properties. Altogether, the results revealed that seed crop years and especially locations affect pea protein quality, calling for proper adaptation strategies.

A Multi-Isotopic Chemometric Approach for Tracing Hazelnut Origins.

High-value products, such as hazelnuts, are particularly vulnerable to fraud due to their price dependence on geographical origin. Guaranteeing hazelnuts' authenticity is essential for consumer trust and safety. Stable isotope analysis has become a reference method for origin authentication as it is reliable, robust, and easily transferable across laboratories. However, multiple isotopic markers coupled with chemometric techniques are often needed to authenticate food provenance accurately. In this study, we focused on assessing the potential of bulk δ18O, along with δ2H and δ13C of the main fatty acids, as hazelnut-origin authenticity markers. PLS-DA classification models were developed to differentiate samples (n = 207) according to their region of origin. This multi-isotopic approach provided promising external validation results, achieving a 94% global correct classification rate in discriminating hazelnuts from regions with distinct geographical and environmental conditions. This study lays the groundwork for further model development and evaluation across additional production areas and harvest years.

Metabolic Profiling and Stable Isotope Analysis of Wines: Pilot Study for Cross-Border Authentication.

Globalization and free market dynamics have significantly impacted state economies, particularly in the wine industry. These forces have introduced greater diversity in wine products but have also heightened the risk of food fraud, especially in high-value commodities like wine. Due to its market value and the premium placed on quality, wine is frequently subject to adulteration. This issue is often addressed through regulatory trademarks on wine labels, such as Protected Designation of Origin (PDO) and Protected Geographic Indication (PGI). In this context, the metabolic profiles (organic acids, carbohydrates, and phenols) and stable isotope signatures (δ13C, δ18O, D/HI, and D/HII) of red and white wines from four agroclimatically similar regions were examined. The study explored how factors such as grape variety, harvest year, and geographical origin affect wine composition, with a particular focus on distinguishing samples from cross-border areas. Multivariate statistical analysis was used to assess the variability in wine composition and to identify distinct groups of samples. Preliminary results revealed that organic acids and volatile compounds were found in lower concentrations than carbohydrates but were significantly higher than phenols, with levels ranging between 1617 mg/L and 6258 mg/L. Carbohydrate content in the wines varied from 8285 mg/L to 14662 mg/L. Principal Component Analysis (PCA) indicated certain separation trends based on the variance in carbohydrates (e.g., fructose, glucose, galactose) and isotopic composition. However, Discriminant Analysis (DA) provided clear distinctions based on harvest year, variety, and geographical origin.

Characterization of Unfractionated Polysaccharides in Brown Seaweed by Methylation-GC-MS-Based Linkage Analysis.

This study introduces a novel approach to analyze glycosidic linkages in unfractionated polysaccharides from alcohol-insoluble residues (AIRs) of five brown seaweed species. GC-MS analysis of partially methylated alditol acetates (PMAAs) enables monitoring and comparison of structural variations across different species, harvest years, and tissues with and without blanching treatments. The method detects a wide array of fucose linkages, highlighting the structural diversity in glycosidic linkages and sulfation position in fucose-containing sulfated polysaccharides. Additionally, this technique enhances cellulose quantitation, overcoming the limitations of traditional monosaccharide composition analysis that typically underestimates cellulose abundance due to incomplete hydrolysis of crystalline cellulose. The introduction of a weak methanolysis-sodium borodeuteride reduction pretreatment allows for the detection and quantitation of uronic acid linkages in alginates.

The use of age and growth techniques to quantify the age structure of carryover hybrid catfish (female Channel Catfish × male Blue Catfish) in commercial ponds in West Alabama

AbstractObjectiveIn West Alabama, catfish Ictalurus spp. producers routinely face the challenge of fish that exceed market size (aka “Big Fish”) in their commercial ponds. These fish are skilled at evading seine nets during harvest and can increase in size significantly before subsequent harvests occur. This is problematic for catfish producers because processing plants prefer catfish within the 0.45–1.81‐kg range and farmers are paid a premium price for catfish of this size. Due to their larger size and growth potential, hybrid catfish (female Channel Catfish Ictalurus punctatus × male Blue Catfish I. furcatus) can become a more significant issue than Channel Catfish if they evade harvest. The objective of this study was to describe and quantify the age structure and growth rate of hybrid catfish that evade capture and remain in commercial ponds following harvest and grow beyond acceptable market size as defined by catfish processing plants (i.e., Big Fish).MethodsHybrid catfish were collected from 12 recently harvested commercial ponds in West Alabama from December 2021 to August 2022 using an electroshocking boat. Total length (mm), body weight (kg), and sex of collected fish were recorded, and lapilli otoliths were removed to estimate fish age and determine total length and total body weight at estimated ages.ResultIn this study, 1005 hybrid catfish were collected with the successful age estimation for 1001 catfish, ranging from 1 to 11 years. Results of this study indicate that hybrid catfish exceeded the premium size threshold in 2.72 years ± 8 months. Additionally, from age 2 to age 3, the average hybrid catfish gained 2.90 kg, growing from 0.40 to 3.30 kg. Growth rate was significantly affected by sex; males overall were predicted to weigh more than females based on the weight‐at‐age model.ConclusionHybrid catfish should be completely harvested from commercial ponds following 1 year of harvest to receive the premium price per kilogram of live fish. If a complete harvest is unsuccessful, farmers can receive a discounted price per kilogram of leftover hybrid catfish based on current market trends.

The Cost of Hatchery Straying: An Economic Case Study on Alaska Pink Salmon

Augmenting harvest using hatchery-produced salmon relies on fish returning to intended sites for capture. However, not all do – some stray, evading capture and entering wild spawning grounds, thus representing foregone yield. Here we ask, “what is the theoretical loss to harvesters as a result of straying?” We applied existing stray estimates and ex-vessel values from the world’s largest pink salmon hatchery-fishery program: Prince William Sound, Alaska, across three return years with full accounting of system wide harvest, escapement, and straying, to examine the value of strays under a range of scenarios that varied the component of the harvesting sector that might catch strays. In this system, approximately 1-5% of returning hatchery fish are estimated to stray away from release sites, which translates to approximate 0.8 - 4.5 million fish. We found that these strays were worth between $1 and $8 million per year, depending on the scenario and harvest year examined. While many important assumptions factor into this evaluation, our intention is for this work to spark dialogues about the economic tradeoffs associated with investing in stray reduction technologies, complementing the well-studied eco-evolutionary costs and benefits of straying.

Antioxidant and antibacterial extracts from rambutan (Nephelium lappaceum) skins: Exploring the Potential of Transforming Agricultural Byproducts into Functional Supplements

Rambutan (Nephelium lappaceum L.) is a tropical fruit characterized by its oval shape and hairy skin, primarily valued for its juicy pulp. The peels, constituting 45% of the fruit’s weight, are a source of valuable compounds like geraniin, ellagic acid, and quercetin. These peels possess antimicrobial properties effective against various bacteria, making them suitable for food preservation and packaging. Additionally, rambutan extracts hold promise as supplements in animal feed, enhancing growth and reducing methane production. This research delves into the antioxidant and antimicrobial attributes of diverse rambutan varieties. The skin (exocarp) of rambutan fruits from three Costa Rican cultivars -Creole, Rongrein, and Yellow- were collected and processed. Total polyphenolic content (TPC), proanthocyanidins, antioxidant activity, geraniin content, and antimicrobial activity were determined for the three varieties. Also, proanthocyanidin-enriched fractions from rambutan extracts were generated and analyzed. The results revealed TPC and antioxidant activity variations among different rambutan varieties and harvest years. All rambutan extracts displayed antimicrobial activity. In conclusion, the research underscores the rich antioxidant content in rambutan peels, irrespective of the variety, and underscores their potential for use in both human and animal nutrition due to their chemical composition.

Ensiling sugar beets: Effect of mixer feed used for co-ensiling on fermentation products and losses when ensiled in vacuum bags

Co-ensiling beets with other feeds allows for year-round feeding of beets and reduces the risk of dry matter (DM) loss as effluent from the silage. This study aimed to evaluate the effect of co-ensiling high DM beets with maize and grass/clover silage, grass seed straw, fresh beet pulp, and high DM concentrates (dried beet pulp, wheat distillers’ grain solubles; DDGS, wheat bran, rapeseed meal, sunflower meal, soybean hulls, and maize gluten feed) on gaseous weight loss (GWL), loss of effluents, and silage quality. Beets from harvest year 2021 were used to produce two sets of silages in laboratory silos, resulting in a total of 2 pure beet silages and 12 mixed beets silages. GWL was measured by weighing the laboratory silos until 181 days of ensiling. Fermentation was terminated by freezing after 30, 92, and 181 days of ensiling where loss of effluent was also measured. Total GWL was highest in the two pure beet silages (mean ± SEM; 282 ± 5.47 and 250 ± 7.94 g/kg DM, respectively), and differed among the mixed silages depending on mixer feed. Effluent was only observed in the pure beet silage in Set 1. Silage DM content at 181 days of ensiling was lowest for the two pure beet silages (180 ± 10.9 and 165 ± 5.95 g/kg). For all silages, pH was below 4.25 by 30 days of ensiling. Ethanol concentrations at 181 days of ensiling were highest in the two pure beet silages (345 ± 11.5 and 287 ± 11.8 g/kg DM). L-lactate content of pure beet silages was 38.4 ± 1.85 and 31.1 ± 1.21 g/kg DM at 181 days of ensiling. In Set 1, L-lactate content was lower in beets ensiled with maize silage, grass seed straw, dried beet pulp, or DDGS compared to pure beet silage. In Set 2, L-lactate content was higher in beets ensiled with maize gluten feed compared to pure beet silage. Silage concentration of NH3 varied depending on mixer feed. The NH3 content at 181 days of ensiling was 0.817 ± 0.626 and 2.05 ± 0.601 g/kg DM for pure beet silages and was highest in beets ensiled with grass/clover silage in both silage sets (16.4 ± 0.63 and 17.6 ± 0.60 g/kg DM). Co-ensiling beets with forages, high DM concentrates, and protein-rich feeds included in this study lowered fermentation weight loss, eliminated the loss of effluent, and resulted in silages of good fermentation quality.

Multi-Year Insights into Industrial Hemp Growth in a Mediterranean Climate

Hemp (Cannabis sativa L.) is a rapidly growing plant with multipurpose uses, and the optimal combination of yield and quality of hemp products (fibers, inflorescences, or seeds) may provide economic opportunities to uncover the full spectrum of its capabilities. The presented experimentation took place over seven years (2017–2023) in Greek climatic conditions for fourteen (14) registered monoecious and dioecious varieties. It can be concluded that the production of biomass, fiber, and seed weight were different not only between varieties but also from year to year. Despite significant variation between harvest years in biomass yield, the extracted fiber was relatively constant. Moreover, not only the dioecious varieties but also the monecious varieties could be effectively grown for biomass production in Greece. Regarding fiber production, monoecious varieties had the highest yields, apart from the dioecious Kompolti variety, which was the most fiber-productive. Under the experimentation conditions, early flowering varieties were most suited for seed production, and the KC Dora variety produced the heavier seeds. Generally, the Futura 75 variety was one of the most productive varieties for biomass and seed weight, while the Bialobrzeskie variety produced the greatest amounts of fiber.

Effect of the Association of Levels of Potassium and Nitrogen from Coated Urea on the Forage Potential of Cactus Pear in Brazilian Savannah Soil

ABSTRACT The development of methods that aim to increase the water use efficiency in agricultural systems should be part of the objectives of research, and the cultivation of plants of lower water requirements, such as cactus pear, can be a good option. The purpose of this study was to evaluate the effect of the association of potassium (K) and nitrogen (N) levels from coated urea, in two harvest years, on the agronomic characteristics and nutritive value of Nopalea cochenillifera cv Doce. A randomized block design in a 2 × 4 × 2 factorial arrangement was adopted. The factors corresponded to two levels of K (40 kg and 60 kg ha−1 year−1), four levels of N (0, 60, 120, and 240 kg ha−1 year−1) and two harvest years (Years I and II). The plants were evaluated for growth, yield, chemical, and mineral composition, and nutritive value. The levels of K affected only plant height and K content in the plant. The agronomic variables and contents of ether extract and crude protein (CP) linearly increased along with the levels of N from the coated urea. There was a significant effect of interaction between N levels and harvest year on the contents of NDF, NDFap, NFC, fraction A+B1, Ca, and Mg. The level of 40 kg K ha−1 year−1 associated with 240 kg N ha−1 year−1 from coated urea provided the best results for the characteristics of growth, yield, and nutritive value of the cactus pear.

Acacia seeds: compositional variation based on species, growing locations and harvest years

SummaryThree different Acacia seeds (A. retinodes, A. provincialis and A. tenuissima) harvested from different locations and in different years were analysed for their variations in proximate and mineral composition. Results showed no one species had the highest content across all proximate and mineral analyses, for example, A. retinodes Harmans 2020 had the highest ash (3.7%), A. retinodes Harmans 2022 had the highest protein content (31.3%), A. tenuissima Hindmarsh 2020 had the highest fat content (18.5%) and A. provincialis Tarrington 2022 had the highest magnesium content (469 mg/100 g). Principle component analysis was carried out to determine the effect of species, harvest locations and years on the chemical composition. A biplot of the first two principal components with a total of 60.5% variation showed clustering based on harvest years. The compositions of the Acacia seeds were determined to be affected by species, harvest location and year differences. However, a complete gene–environment interaction study is needed to validate this.

An Evaluation of Different Sweet Olive Cultivars with Different Ripening Degrees Grown in the Puglia Region, Southeastern Italy

Some olive cultivars grown in southeastern Italy are characterized by the production of olives with a reduced level of bitterness. They are known as sweet olive cultivars and fruits are usually consumed directly or cooked without any debittering process, offering either health benefits to consumers, thanks to the high content of antioxidants, or an economic benefit to farmers for their higher price with respect to both table and oil olives. This study evaluates and compares the organoleptic, pomological, chemical, and physical parameters of seven sweet olive cultivars at different ripening degrees in the Puglia region over 8 weeks of maturity stage for two consecutive seasons (2022 and 2023). The organoleptic evaluation was performed by a restricted panel of usual consumers/experts of sweet olives. The results showed a higher preference for the olive cultivars locally named Triggiano Dolce, Cerasella, and Mele. Significant differences in weight, length, and width of the fruits were observed based on both cultivar and year. The phenolic composition of olive cultivars was significantly affected by both cultivar and harvest year, with Cazzinicchio and Cellina di Nardò having the highest total polyphenols. The analysis of water fraction extracted from olive samples by liquid chromatography coupled with mass spectrometry led to the identification of eleven compounds belonging to the secoiroids, phenylpropanoids, phenylethanolids, and flavonoids classes. The comparison of these compounds among the studied cultivars highlighted significant differences.

Genetic parameters and chemical characterization of conilon coffee accessions under irrigation in the Cerrado

The objective of this study was to identify the genetic, phenotypic and environmental parameters related to chemical compounds associated with beverage quality in a conilon coffee collection, grown in an irrigated system, in the Cerrado. The experiment was carried out at Embrapa Cerrados using green grains harvested in two years from 84 genotypes of the cultivar Robusta Tropical. Caffeine content, protein, ether extract, total soluble solids, pH and titratable acidity were evaluated. The data were subjected to analysis of variance. Significant differences were observed at 1% probability among accessions for all evaluated chemical characteristics in both harvest years. The high heritability, genetic coefficients of variation and selective accuracy reveal the potential for achieving genetic gains via the selection of genotypes adapted to the irrigated system in the Cerrado combined with high beverage quality.

Two new qPCR assays for detecting and quantifying the Aspergillus flavus and Aspergillus parasiticus clades in maize kernels

AbstractThe fungi of Aspergillus section Flavi can produce carcinogenic mycotoxins—aflatoxins (AFs)—of two types: types B and G (AFBs and AFGs). AFs are highly hazardous for human and animal health. Their levels in food and feed are therefore highly regulated, with a low acceptable limit for AF content. In France, climate change has led to the detection of AFs in maize harvests since 2015. Mycoflora analyses have identified two species, A. flavus (producing AFBs) and A. parasiticus (producing both AFBs and AFGs), as responsible for this AF contamination. However, mycoflora analysis is a time‐consuming method that cannot readily be applied to large numbers of samples. We propose here an alternative clade‐specific functional TaqMan quantitative PCR method based on the calmodulin gene for distinguishing between the A. flavus clade (AfC) and the A. parasiticus clade (ApC). We applied this method to 553 maize samples collected in three different harvest years (2018–2020). Both clades were detected in about 40% of the samples tested. As expected, we observed significant positive correlations between AFBs and AfC DNA (R2 = 0.708), and between AFGs and ApC DNA (R2 = 0.885). This method will be useful for the rapid, simple and cheap characterization of maize grain contamination with Aspergillus section Flavi. This method will make it possible to study the relationship between agroclimatic conditions, AF content and species prevalence, to facilitate the anticipation of AF risks due to global warming in France.

Impact of genotypic variation and cultivation conditions on the techno-functional characteristics and chemical composition of 25 new Canadian quinoa cultivars

The utilization of quinoa in food production requires comprehensive information on its processing characteristics. Twenty-five new quinoa cultivars developed by the Northern Quinoa Breeding Program, grown in three Canadian locations over two seasons, were characterized for their proximate composition, pasting properties, thermal properties, water absorption index, water solubility index, foaming capacity, foaming stability, oil holding capacity, and emulsion activity crucial for potential food applications. Results showed significant variations in the proximate composition among the cultivars, which was also influenced by the growing location and harvest year. Significant differences (p < 0.05) were also observed in the pasting properties, thermal stability, hydration properties, foaming properties, oil holding capacity, and emulsion activity. The hierarchical cluster and principal component analyses were associated with five distinct clusters of quinoa cultivars, each with unique techno-functional attributes, suggesting their potential for different food applications. These findings emphasize the need for further research to explore the performance of quinoa flours in specific food products and their impact on end-product quality.

Assessment of Selected Chemical and Morphological Properties of Lonicera var. kamtschatica and Lonicera var. emphyllocalyx Treated with Gaseous Ozone.

Lonicera caerulea L. fruits are a rich source of vitamins, organic acids, and phenolic compounds, which are characterised by their health-promoting properties. The content of bioactive compounds in this fruit may vary depending on the cultivar and the harvest date. This study analysed the effect of applying 5 ppm gaseous ozone for 1, 3, and 5 min on the chemical properties of L. kamtschatica varieties and newly created clones of L. emphyllocalyx for three years of cultivation. The fruits harvested from L. emphyllocalyx, depending on the year of harvest, had significantly larger size and weight compared to L. kamtschatica. On average, the acidity of the L. emphyllocalyx clones was 6% higher than other tested varieties. The average content of ascorbic acid was highest in L. emphyllocalyx clone '21-17'-57.80 mg·100 g-1; the year of harvest will significantly affect the content of vitamin C, reaching the highest level in 2022-53.92 mg·100 g-1. The total content of polyphenols was significantly dependent on the year of cultivation; reaching, on average, 54.8% more in 2022 compared to the rest of the years. The total antioxidant value using the FRAP, DPPH, and ABTS methods varied depending on the variety; exposure to ozone significantly increased the antioxidant value in each case. On the basis of the study, both botanical varieties can be used in food processing. Gaseous ozone exposure can significantly influence chemical composition, increasing the health-promoting value of fruit.

Harvest of transboundary grey wolves from Yellowstone National Park is largely additive

Abstract Large carnivores are globally threatened due to habitat fragmentation and loss, prey depletion and human exploitation. Human exploitation includes both legal and illegal hunting and trapping. Protected areas can create refugia from hunting and trapping; however, hunting can still threaten wide‐ranging large carnivores when they leave these areas. Large carnivore reintroductions to protected areas are often motivated to restore ecological processes, including wolf reintroduction to Yellowstone National Park (YNP). Determining if harvest is compensatory or additive is essential for informed conservation strategies, as it influences the overall impact on wolf populations and their ecosystems. If harvest was compensatory, then increasing harvest pressure outside YNP should not decrease overall survival for transboundary wolves. Alternatively, if increasing harvest was additive, then increasing harvest pressure outside YNP should decrease overall survival for transboundary wolves. We tested the effects of variable harvest pressure following delisting on the survival of YNP grey wolves (Canis lupus) from 1995 to 2022. We defined three harvest levels: no harvest, harvest with limited quotas and unlimited harvest. We used Cox‐proportional hazards models and cumulative incidence functions to estimate survival rates, factors affecting survival and cause‐specific mortality between these three harvest periods to test predictions of the additive mortality hypothesis. Most harvested wolves that primarily lived in YNP were killed adjacent to the park border. Cox‐proportional hazards models revealed that mortality was highest during years of unlimited harvest during winter outside YNP. Cause‐specific mortality analyses showed that natural mortality from other wolves and harvest were the two leading causes of death, but that harvest mortality had additive effects on wolf mortality. Wolf survival decreased with increased harvest mortality, while natural mortality remained relatively unchanged. Synthesis and applications. High rates of additive harvest mortality of wolves could negatively impact wolf survival in YNP. Harvest mortality of transboundary wolves is additive possibly due to source‐sink dynamics of uneven spatial susceptibility of wolves to harvest mortality across protected area borders, as well as effects of harvest on complex social dynamics of wolves in YNP. Transboundary management of large carnivores is challenging, yet cooperation between agencies is vital for wolf management in and around YNP. Our results support the use of small quota zones surrounding protected areas, that minimize transboundary mortality impacts on large carnivores living primarily inside protected areas.