Does the Atlantic Cod (Gadus morhua) Have a Future In The Gulf of Maine?

Brown University Center For Environmental Studies
Spring 2003

Trends in Commercially-Caught Cod Length and Commercial Landings

As was seen in the previous pages the trends in the length of commercially-landed cod have increased from approximately 60 cm in 1982 to approximately 68 cm in 2000. During this same time period commercial landings have drastically decreased from approximately 51 million cod to just over 10 million cod. Looking at these two variables together produces a graph that suggests an inverse relationship between commercial landings in numbers and the average size of the commercial cod that has been caught. That is, as one trend increases the other trend decreases, and vice versa.

Graph created by E. Brazer Jr.

Here we see that as landings increase the average size of the cod decreased, and vice versa. During the years that fishers were catching the most cod, those were the years producing the cod with the smallest average length. This is clear between 1989 and 1990 where commercial landings skyrocketed and average length dropped. 1987 saw a spike in the trend in length (up approximately 4 cm from the previous year) and a related decline in landings numbers.

This may be a sign that fishers are catching proportionately more of the smaller-sized cod than the larger cod. If a fisherman lands an exceptionally large tow then there will be more fish of "below/average" size than fish of very large size. One year where we do not observed this relationship is during the last year of the study- 2000. Here average length has steadily increased with the commercial landings increasing as well. This may be indicative of the fishers catching a larger proportion of larger cod, or it may show that there is an increase in the average length of the cod within the Gulf of Maine population. However it is too early to determine this.