Scientists tracked sharks near fishing docks in Australia to understand why they keep coming back. Using special tags and analyzing what the sharks ate, researchers found that two types of sharks—dusky and Galapagos sharks—visit the docks regularly but on different schedules. While the sharks do eat some leftover fish scraps from the docks, this isn’t their main food source. The study shows that sharks aren’t becoming dependent on human food, but rather making occasional visits to supplement their natural diet. These findings help us understand how human activities affect shark behavior and can guide better waste management practices.

The Quick Take

  • What they studied: How sharks behave and eat when they visit fishing docks where humans discard fish waste
  • Who participated: 18 dusky sharks and 16 Galapagos sharks tracked near Norfolk Island, Australia from 2021 to 2024
  • Key finding: Sharks visited the docks about once every four days, spending roughly 3 hours there daily, but fish scraps made up only a small part of their diet, suggesting they weren’t becoming dependent on human food
  • What it means for you: If you live near coastal areas with fishing activity, this research suggests sharks aren’t becoming dangerous scavengers dependent on human waste—they’re just occasionally stopping by for a snack while maintaining their natural hunting habits

The Research Details

Scientists used two main tools to track shark behavior. First, they attached acoustic tags (small electronic devices) to 34 sharks—18 dusky sharks and 16 Galapagos sharks. These tags sent signals to underwater receivers near the fishing docks, allowing researchers to know exactly when sharks visited and how long they stayed. Second, the researchers analyzed what the sharks ate by examining fatty acids and stable isotopes in their blood and tissue samples. These are like chemical fingerprints that reveal what food sources an animal has been eating.

The study ran for about three years (2021-2024) at Norfolk Island in Australia, a remote location with active fishing operations. By combining the location data from the tags with the dietary information, scientists could determine whether sharks were actually eating the discarded fish from the docks or if they were visiting for other reasons.

This approach is powerful because it doesn’t just tell us where sharks go—it tells us what they’re actually eating, which reveals their true relationship with the fishing docks.

Understanding shark behavior around human activities is crucial for both shark conservation and public safety. If sharks were becoming dependent on human food waste, it could change their natural behavior in dangerous ways. This study helps answer important questions: Are we accidentally training sharks to expect food from humans? Are we changing their natural hunting patterns? By using both tracking technology and dietary analysis, researchers can give us a complete picture rather than just guessing based on observation alone.

This study has several strengths: it tracked individual sharks over a long period (3 years), used multiple scientific methods to verify findings, and studied a real-world situation rather than controlled laboratory conditions. However, the sample size is relatively modest (34 sharks total), and the study focuses on one specific location, so results may not apply to all shark populations everywhere. The research was published in Scientific Reports, a reputable peer-reviewed journal, which means other scientists reviewed the work before publication.

What the Results Show

The two shark species showed interesting differences in their visiting patterns. Dusky sharks typically arrived in the early afternoon and stayed until sunset, while Galapagos sharks arrived at dusk and left in the early morning. This means they were using the docks at different times, which reduces competition between the species. On average, each shark visited the docks about once every four days and spent roughly three hours there per visit.

Surprisingly, when scientists analyzed what the sharks had eaten, they found that both species had very similar diets overall. More importantly, discarded fish from the docks made up only a small portion of what they ate. The sharks that visited the docks most frequently did have slightly more fish scraps in their stomachs compared to sharks that visited less often, but this difference was modest.

These findings suggest that while sharks do eat some leftover fish at the docks, they’re not relying on this food source. Instead, they appear to be making occasional visits to supplement their natural diet of wild fish they hunt themselves. The sharks aren’t becoming dependent on human food waste the way some animals (like bears at campsites) can become.

The study revealed that the temporal partitioning—meaning the sharks using the docks at different times—is an interesting adaptation. This scheduling difference allows both shark species to use the same resource without constantly competing with each other. Additionally, the research showed that only a subset of the tagged shark population regularly visited the piers, suggesting that not all sharks in the area are attracted to the docks equally. Some sharks preferred to stick with their natural hunting grounds.

Previous research has shown that some shark species can become conditioned to expect food from humans, similar to how seagulls learn to scavenge at beaches. This study adds important nuance to that understanding by showing that proximity to human food doesn’t automatically lead to behavioral conditioning. The findings align with other research suggesting that sharks maintain their natural foraging behaviors even when human food sources are available, though they may occasionally take advantage of easy meals.

The study tracked only 34 sharks at one location over three years, so we can’t be certain these patterns apply to all shark populations or all fishing areas. The researchers couldn’t determine why sharks visit the docks—whether it’s purely for food or if other factors (like water temperature or shelter) also play a role. Additionally, the study couldn’t track what happened to sharks that weren’t tagged, so we don’t know if the tagged sharks represent typical behavior for their species. Finally, dietary analysis can only tell us what sharks ate recently, not their complete feeding history.

The Bottom Line

Based on this research, fishing operations can likely continue current waste disposal practices without major concern that sharks are becoming dangerously dependent on human food. However, improving waste management—such as better containment of fish scraps—would still be beneficial for overall ocean health and to minimize any potential attraction of sharks to docks. Confidence level: Moderate, as this is based on one location and relatively small sample size.

Fishing industry managers and coastal communities should care about these findings, as they help guide sustainable practices. Marine biologists and shark researchers will find this valuable for understanding shark behavior. Coastal residents and tourists may find it reassuring that sharks visiting fishing areas aren’t becoming aggressive scavengers. However, people should still follow standard water safety practices around fishing docks regardless of these findings.

These are long-term behavioral patterns observed over three years. Changes in shark behavior or diet would likely take months to years to become apparent, not days or weeks.

Want to Apply This Research?

  • If using a marine observation app, track shark sightings near fishing areas by date and time of day to see if local patterns match the study’s findings of different species visiting at different times
  • For coastal residents or fishers, use this research to inform better waste management practices—properly dispose of fish scraps rather than letting them accumulate, which can help maintain natural shark behavior patterns
  • Establish a long-term observation log of shark activity near fishing operations, noting time of day, species, and frequency of visits to track whether local shark behavior changes over seasons or years

This research describes shark behavior at one specific location and should not be used as a basis for making decisions about water safety or shark interactions. Always follow local water safety guidelines and heed warnings from authorities regarding shark activity. This study does not indicate that sharks are safe to approach or feed. If you encounter a shark, maintain distance and contact local wildlife authorities. This information is for educational purposes and should not replace professional advice from marine biologists or wildlife experts.