La morue : chronique d'un rétrécissement

Summary

In the northern waters of Norway, scientists aboard the 'Star Atlantic' are investigating the mystery of shrinking cod. Once abundant and large, cod have been steadily decreasing in size since the 1950s, with fishing intensifying the problem. Scientists hypothesize that this may be due to ecological changes, where fewer fish lead to faster maturation of those left. However, an evolutionary theory suggests that fishing is driving cod to evolve smaller sizes to avoid being caught. This shift poses economic challenges for Norway's fishing industry, with concerns that evolutionary changes may be irreversible. Genetic research is underway to understand the full impact on cod populations.

Takeaways

• 😀 The cod population off the coast of Norway is shrinking, with the once-large cod becoming progressively smaller.
• 😀 Scientists aboard the 'Star Atlantic' are investigating why cod are shrinking, using various methods to understand the phenomenon.
• 😀 Cod has been a crucial part of Norway’s fishing industry for centuries, forming an essential food source and livelihood for coastal populations.
• 😀 Starting in the 1950s, fishermen began noticing smaller cod in their nets, and the large cod gradually disappeared.
• 😀 Scientists study the age and size of cod by analyzing the otoliths, or ear bones, which contain growth rings that help determine their age.
• 😀 Since the 1940s, there has been an increase in fishing intensity, leading to a decline in cod age and size at maturation.
• 😀 One hypothesis suggests that fewer fish in the ocean means available resources can support faster growth and quicker maturation of the remaining fish.
• 😀 Despite fishing regulations aimed at protecting the cod stock, such as mesh size limits and quotas, the cod population continues to shrink.
• 😀 Evolutionary biologists theorize that cod may have evolved to become smaller to escape being caught in fishermen's nets more effectively.
• 😀 Larger cod are trapped in fishing nets, while smaller fish can escape through the mesh, causing fishing to select for smaller fish over time.
• 😀 Fishing practices, which target the largest fish, may be driving evolutionary changes by preventing large cod from reproducing, thus favoring smaller cod.
• 😀 The shrinking cod is a serious economic concern for Norway, where larger cod bring in higher market profits, potentially affecting the nation's fishing industry.
• 😀 Evolutionary changes in cod are difficult to reverse, especially without genetic proof, although scientists are sequencing the cod genome to understand these changes better.
• 😀 Researchers are working towards understanding the genetic basis for the evolutionary changes in cod, hoping to find solutions to protect future fish stocks.

Q & A

What is the strange phenomenon scientists are investigating off the coast of Norway?

Scientists are investigating the shrinking size of cod fish in the northern European seas, particularly around Norway. Cod, which were once much larger, have been getting smaller over time.

How do scientists determine the age of cod fish?

Scientists determine the age of cod fish by studying their ear bones, known as otoliths. These bones grow in rings, similar to tree rings, and the number of rings indicates the age of the fish.

What hypothesis explains the shrinking cod population?

One hypothesis is that with fewer fish in the ocean, the remaining cod can access more food and grow faster, leading to earlier maturation but smaller sizes.

What theory do evolutionary biologists suggest to explain the shrinking cod?

Evolutionary biologists suggest that the cod have evolved to escape fishing nets by becoming smaller. The smaller fish are able to slip through the mesh of the nets, while the larger fish get trapped.

How does fishing impact the cod population, according to scientists?

Fishing targets the larger fish, which are more valuable as food and resources. This increases the danger for larger fish, while smaller fish are less targeted, leading to a preference for smaller cod in the population over time.

What is the economic concern related to shrinking cod?

The shrinking size of cod poses an economic risk because smaller cod are less profitable, and the fishery industry relies on larger fish for greater yield and profit.

What role does fishing regulation play in the situation?

Fishing regulations such as minimum mesh sizes and quotas have been introduced to limit the amount of fish caught, but the cod population has still not returned to its original size, indicating deeper ecological and evolutionary impacts.

Why is it difficult to reverse the evolutionary changes in cod?

If the changes in cod are driven by evolutionary factors, they could be more difficult to reverse because evolutionary processes are slower and involve genetic changes, which require much longer timescales to address.

What are scientists working on to understand the genetic basis of the shrinking cod?

Scientists are sequencing the cod genome to understand the genetic basis of the changes occurring in the population. This research is still in progress, but it may eventually provide a clearer picture of the genetic factors involved.

Will the cod population ever return to its previous size, and what is the long-term goal?

It remains uncertain whether the cod population will return to its original size, but studying evolutionary theory and understanding the genetic changes could help ensure the protection and sustainable management of cod stocks in the future.