Cod Spawning Times
What are the times of spawning of the different cod stocks in the northwest Atlantic fishery
**Spawning times for Atlantic cod (*Gadus morhua*) stocks in the Northwest Atlantic vary by region, with a general pattern of earlier spawning in southern areas and later (or more protracted) spawning farther north. Timing can also shift with winter severity or other environmental conditions (e.g., peak earlier in milder winters).** (LINK)
Major stocks/components and their typical spawning periods (based on egg surveys, maturity data, ichthyoplankton programs like MARMAP/GLOBEC, and historical syntheses) are summarized below. Peaks and ranges are approximate and can show interannual variation.
### Georges Bank (NAFO 5Z / US-Canada shared)
– Season: Primarily November–May (sometimes starting as early as September/October; limited activity in summer).
– Peak: February–March (often ~60% of spawning between late February and early April; median around mid-March).
– Notes: Spawning is widespread but concentrated on the Northeast Peak. It tends to begin on the southern flank and progress northward/westward. Western areas (e.g., Nantucket Shoals/Great South Channel) often peak earlier (November–December). ).** (LINK)
### Gulf of Maine (NAFO 5Y)
– Overall season: November–May (or into early summer in some northern areas).
– Distinct sub-components (genetically separable):
– **Winter spawners** (western GOM): Peak November–December (or October–January); key areas include Stellwagen Bank and nearby grounds.
– **Spring spawners** (western GOM): Peak May–June (or April–July); areas such as Ipswich Bay and Jeffreys Ledge.
– Notes: Spawning generally occurs later farther north (e.g., January–February in Massachusetts Bay; February–April north of Cape Ann; March–May farther north toward Mt. Desert Island). (LINK)
### Southern New England / areas west of the Great South Channel and Nantucket Shoals
– Season: Often begins in fall (October/November) and extends into spring (to April or later).
– Peak: Frequently November–December or late winter–early spring, with variability by specific site (e.g., Cox Ledge November–April, peaking November–March). (LINK)
### Southern Grand Bank (NAFO 3NO)
– Peak: May (or May–June).
– Range: April–June. (LINK)
### Flemish Cap (NAFO 3M)
– Peak: March.
– Range: February–April.
**Additional context**:
– Spawning is typically near-bottom, with pelagic eggs and larvae. Preferred temperatures are often in the 2–10°C range for viable hatching.
– Latitudinal trends exist but are not perfectly consistent across all northern stocks; plankton timing, temperature, and retention also influence success.
– Management units (US, Canadian, NAFO) may group multiple spawning components. Recent genetic and fishermen’s knowledge studies have refined understanding of sub-structure, especially in the Gulf of Maine and Georges Bank.
– Data sources include long-term surveys (e.g., MARMAP), maturity staging, and compilations such as those by Brander and others. For the most current stock-specific details, refer to the latest assessments from NOAA Fisheries, DFO Canada, or NAFO.
These timings support measures such as seasonal closures to protect spawning aggregations.